Delving into the enigmatic world of fractions on the TI-84 Plus calculator may seem like a daunting task, but fear not! This comprehensive guide will equip you with the knowledge and techniques to navigate this mathematical realm with ease. Whether you’re a seasoned math wizard or an aspiring numerical enthusiast, this insightful article will illuminate the path to fraction mastery on your trusty TI-84 Plus.
First and foremost, let’s break down the basics: fractions are simply numbers expressed as a ratio of two integers. On the TI-84 Plus, you can enter fractions in two ways. For instance, to enter the fraction 1/2, you can either type “1/2” or “1 รท 2.” The calculator will automatically recognize the fraction and store it internally. Alternatively, you can use the dedicated “Frac” button to convert a decimal into its fractional equivalent. Once you’ve inputted your fraction, you’re ready to embark on a world of mathematical possibilities.
The TI-84 Plus offers an array of powerful functions that make working with fractions a breeze. For example, you can simplify fractions using the “simplify” command, which reduces fractions to their lowest terms. Additionally, the calculator provides functions for addition, subtraction, multiplication, and division of fractions, allowing you to perform complex calculations with ease. And if you need to convert a fraction to a decimal or percentage, the TI-84 Plus has you covered with dedicated conversion functions. By harnessing these capabilities, you’ll be able to tackle fraction-based problems with confidence and precision.
Entering Fractions into the TI-84 Plus
Fractions are an essential part of mathematics, and the TI-84 Plus calculator makes it easy to enter and work with them. There are two main ways to enter a fraction into the TI-84 Plus:
-
Using the fraction template: The fraction template is the most straightforward way to enter a fraction. To use the fraction template, press the "2nd" key followed by the "x-1" key. This will open up the fraction template, which has three parts: the numerator, the denominator, and the fraction bar.
- To enter the numerator, use the arrow keys to move the cursor to the numerator field. Then, use the number keys to enter the numerator.
- To enter the denominator, use the arrow keys to move the cursor to the denominator field. Then, use the number keys to enter the denominator.
- To enter the fraction bar, press the "enter" key.
Once you have entered the numerator and denominator, the fraction will appear on the screen. For example, to enter the fraction 1/2, you would press the "2nd" key followed by the "x-1" key. Then, you would use the arrow keys to move the cursor to the numerator field and press the "1" key. You would then use the arrow keys to move the cursor to the denominator field and press the "2" key. Finally, you would press the "enter" key. The fraction 1/2 would then appear on the screen.
-
Using the division operator: You can also enter a fraction into the TI-84 Plus using the division operator. To do this, simply enter the numerator followed by the division operator (/) followed by the denominator. For example, to enter the fraction 1/2 using the division operator, you would press the "1" key followed by the "/" key followed by the "2" key. The fraction 1/2 would then appear on the screen.
Using the division operator to enter a fraction is often faster than using the fraction template, but it is important to be careful not to make any mistakes. If you make a mistake, the fraction will not be entered correctly and you will need to start over.
Here is a table summarizing the two methods for entering fractions into the TI-84 Plus:
Method | Steps |
---|---|
Fraction template | 1. Press the "2nd" key followed by the "x-1" key. |
2. Use the arrow keys to move the cursor to the numerator field. | |
3. Enter the numerator using the number keys. | |
4. Use the arrow keys to move the cursor to the denominator field. | |
5. Enter the denominator using the number keys. | |
6. Press the "enter" key. | |
Division operator | 1. Enter the numerator. |
2. Press the "/" key. | |
3. Enter the denominator. |
Using the MATH Menu to Convert Decimals to Fractions
The TI-84 Plus calculator offers a comprehensive MATH menu that includes various tools for working with fractions. One of these tools is the "Frac" command, which allows you to convert decimals to their equivalent fractions. This feature is particularly useful when dealing with rational numbers or performing calculations that involve fractions.
To access the Frac command, follow these steps:
- Ensure that your TI-84 Plus calculator is in the "MATH" mode.
- Scroll down to the "Frac" entry in the menu and press "ENTER."
The Frac command requires you to provide the decimal number you want to convert to a fraction. Here’s how to input the decimal:
- After pressing "ENTER," you will see a blinking cursor on the screen.
- Enter the decimal value as you would normally write it, including the decimal point.
- Press "ENTER" again to initiate the conversion.
The TI-84 Plus calculator will perform the conversion and display the result as a fraction. The fraction will be in the simplest form, meaning it will be reduced to its lowest terms. For example, if you enter the decimal 0.75, the calculator will convert it to the fraction 3/4.
Here are some additional points to note about the Frac command:
- The Frac command can only convert terminating decimals to fractions. If you enter a non-terminating decimal (like 0.333…), the calculator will display an error message.
- The calculator will automatically reduce the fraction to its simplest form. You cannot specify the desired form of the fraction.
- The Frac command is particularly useful when you need to convert decimals to fractions for calculations. For example, if you want to add 0.25 and 0.5, you can use the Frac command to convert them to 1/4 and 1/2, respectively, and then perform the addition as fractions.
- The Frac command can also be used to convert fractions to decimals. To do this, simply enter the fraction as a command, e.g., "Frac(1/2)."
Manipulating Fractions Using the FRAC Command
The FRAC command on the TI-84 Plus calculator is a powerful tool for working with fractions. It can be used to convert decimals to fractions, simplify fractions, add, subtract, multiply, and divide fractions, and find the greatest common factor (GCF) and least common multiple (LCM) of two or more fractions.
To use the FRAC command, type the command followed by the numerator and denominator of the fraction in parentheses. For example, to enter the fraction 1/2, you would type: FRAC(1,2).
Once you have entered a fraction using the FRAC command, you can use the calculator’s arrow keys to move the cursor around the fraction. The up and down arrow keys move the cursor between the numerator and denominator, and the left and right arrow keys move the cursor within the numerator or denominator.
You can also use the calculator’s menu to perform operations on fractions. To access the menu, press the [2nd] key followed by the [MATH] key. The menu will appear on the screen. Use the arrow keys to move the cursor to the desired operation and press the [ENTER] key.
The following table summarizes the operations that you can perform on fractions using the FRAC command:
Operation | Syntax | Example |
---|---|---|
Convert a decimal to a fraction | FRAC(decimal) | FRAC(0.5) = 1/2 |
Simplify a fraction | FRAC(numerator, denominator) | FRAC(3,6) = 1/2 |
Add fractions | FRAC(numerator1, denominator1) + FRAC(numerator2, denominator2) | FRAC(1,2) + FRAC(1,3) = 5/6 |
Subtract fractions | FRAC(numerator1, denominator1) – FRAC(numerator2, denominator2) | FRAC(1,2) – FRAC(1,3) = 1/6 |
Multiply fractions | FRAC(numerator1, denominator1) * FRAC(numerator2, denominator2) | FRAC(1,2) * FRAC(1,3) = 1/6 |
Divide fractions | FRAC(numerator1, denominator1) / FRAC(numerator2, denominator2) | FRAC(1,2) / FRAC(1,3) = 3/2 |
Find the greatest common factor (GCF) of two or more fractions | GCD(FRAC(numerator1, denominator1), FRAC(numerator2, denominator2)) | GCD(FRAC(1,2), FRAC(1,3)) = 1 |
Find the least common multiple (LCM) of two or more fractions | LCM(FRAC(numerator1, denominator1), FRAC(numerator2, denominator2)) | LCM(FRAC(1,2), FRAC(1,3)) = 6 |
Adding and Subtracting Fractions on the TI-84 Plus
The TI-84 Plus graphing calculator is a powerful tool that can be used to perform a variety of mathematical operations, including adding and subtracting fractions. To add or subtract fractions on the TI-84 Plus, follow these steps:
- Enter the first fraction into the calculator. To do this, press the “2nd” button followed by the “frac” button. This will bring up the Fraction Editor. Enter the numerator of the fraction into the top field and the denominator into the bottom field. Press the “enter” button to save the fraction.
- Enter the second fraction into the calculator. To do this, repeat step 1.
- To add the fractions, press the “+” button. To subtract the fractions, press the “-” button.
- The result of the operation will be displayed in the calculator’s display. If the result is a mixed number, the integer part of the number will be displayed first, followed by the fraction part. For example, if you add 1/2 and 1/3, the result will be displayed as 5/6.
Here is a table summarizing the steps for adding and subtracting fractions on the TI-84 Plus:
Operation | Steps |
---|---|
Addition |
|
Subtraction |
|
Here are some additional tips for adding and subtracting fractions on the TI-84 Plus:
- You can also use the “math” menu to add or subtract fractions. To do this, press the “math” button and then select the “fractions” option. This will bring up a menu of options for working with fractions, including adding, subtracting, multiplying, and dividing fractions.
- If you are working with a complex fraction, you can use the “complex” menu to enter the fraction. To do this, press the “complex” button and then select the “fraction” option. This will bring up a menu of options for working with complex fractions, including adding, subtracting, multiplying, and dividing complex fractions.
- The TI-84 Plus can also be used to simplify fractions. To do this, press the “math” button and then select the “simplify” option. This will bring up a menu of options for simplifying fractions, including simplifying fractions to their lowest terms, simplifying fractions to mixed numbers, and simplifying fractions to decimals.
Multiplying and Dividing Fractions on the TI-84 Plus
Entering Fractions
To enter a fraction into the TI-84 Plus, use the fraction template:
(numerator / denominator)
For example, to enter the fraction 1/2, type:
(1 / 2)
Multiplying Fractions
To multiply fractions on the TI-84 Plus, use the asterisk (*) key.
(numerator1 / denominator1) * (numerator2 / denominator2)
For example, to multiply 1/2 by 3/4, type:
(1 / 2) * (3 / 4)
The result will be 3/8.
Dividing Fractions
To divide fractions on the TI-84 Plus, use the forward slash (/) key.
(numerator1 / denominator1) / (numerator2 / denominator2)
For example, to divide 1/2 by 3/4, type:
(1 / 2) / (3 / 4)
The result will be 2/3.
Converting Mixed Numbers to Improper Fractions
To convert a mixed number to an improper fraction on the TI-84 Plus, use the following steps:
- Multiply the whole number by the denominator of the fraction.
- Add the numerator of the fraction to the result of step 1.
- Place the result of step 2 over the denominator of the fraction.
For example, to convert the mixed number 2 1/3 to an improper fraction, type:
(2 * 3) + 1 / 3
The result will be 7/3.
Converting Improper Fractions to Mixed Numbers
To convert an improper fraction to a mixed number on the TI-84 Plus, use the following steps:
- Divide the numerator by the denominator.
- The quotient of step 1 is the whole number.
- The remainder of step 1 is the numerator of the fraction.
- The denominator of the fraction is the same as the denominator of the improper fraction.
For example, to convert the improper fraction 7/3 to a mixed number, type:
7 / 3
The result will be 2 1/3.
Practice Problems
- Multiply the fractions 1/2 and 3/4.
- Divide the fractions 1/2 by 3/4.
- Convert the mixed number 2 1/3 to an improper fraction.
- Convert the improper fraction 7/3 to a mixed number.
- Simplify the fraction 12x^2 / 15x.
Answer Key:
- 3/8
- 2/3
- 7/3
- 2 1/3
- 4x
Converting Fractions to Mixed Numbers
Converting fractions to mixed numbers is essential for performing various mathematical operations. A mixed number is a combination of a whole number and a fraction, representing a value greater than 1. To convert a fraction to a mixed number, follow these steps:
1. Divide the numerator (top number) by the denominator (bottom number) using long division.
2. The quotient obtained from the division represents the whole number part of the mixed number.
3. The remainder from the division becomes the numerator of the fraction part of the mixed number.
4. The denominator remains the same as the original fraction.
For example, to convert the fraction 7/3 to a mixed number:
3 ) 7 |
3 2 |
6 |
1 |
Therefore, 7/3 as a mixed number is 2 1/3.
7. Converting Improper Fractions to Mixed Numbers
An improper fraction is a fraction where the numerator is greater than or equal to the denominator. To convert an improper fraction to a mixed number, follow these steps:
- Divide the numerator by the denominator using long division.
- The quotient obtained from the division represents the whole number part of the mixed number.
- The remainder from the division becomes the numerator of the fraction part of the mixed number.
- The denominator remains the same as the original fraction.
Example:
Convert the improper fraction 11/4 to a mixed number:
4 ) 11 |
4 8 |
8 |
3 |
Therefore, 11/4 as a mixed number is 2 3/4.
Converting Mixed Numbers to Fractions
Converting mixed numbers to fractions involves two steps:
1. Multiply the whole number by the denominator of the fraction
For example, if you want to convert 3 1/2 to a fraction, you would multiply 3 by 2 (the denominator of the fraction 1/2) to get 6.
2. Add the numerator of the fraction to the result
Finally, add the numerator of the fraction (1) to the result of the multiplication (6) to get 7. The fraction equivalent of 3 1/2 is therefore 7/2.
Example
Let’s convert 4 3/4 to a fraction.
- Multiply the whole number (4) by the denominator of the fraction (4) to get 16.
- Add the numerator of the fraction (3) to the result of the multiplication (16) to get 19.
Therefore, 4 3/4 is equivalent to the fraction 19/4.
Converting Fractions to Mixed Numbers
Converting fractions to mixed numbers can be done by using the following steps:
1. Divide the denominator of the fraction into the numerator
For example, if you want to convert the fraction 7/2 to a mixed number, you would divide 2 into 7 to get 3 as the quotient.
2. The remainder of the division is the numerator of the fraction part of the mixed number
In this case, there is no remainder, so the fraction part of the mixed number would be 0/2, which can be simplified to just 0.
3. The quotient of the division is the whole number part of the mixed number
Therefore, 7/2 is equivalent to the mixed number 3.
Example
Let’s convert 19/4 to a mixed number.
- Divide the denominator (4) into the numerator (19) to get 4 as the quotient and 3 as the remainder.
- The remainder (3) is the numerator of the fraction part of the mixed number, and the quotient (4) is the whole number part of the mixed number.
Therefore, 19/4 is equivalent to the mixed number 4 3/4.
Table of Conversions
The following table shows the conversions for some common fractions and mixed numbers:
Mixed Number | Fraction |
---|---|
3 1/2 | 7/2 |
4 3/4 | 19/4 |
2 1/3 | 7/3 |
1 3/8 | 11/8 |
5 2/5 | 27/5 |
Finding Least Common Multiples and Denominators
The Least Common Multiple (LCM) of two or more fractions is the smallest positive integer that is divisible by all the denominators of the given fractions. The Least Common Denominator (LCD) of two or more fractions is the smallest positive integer that all the denominators of the given fractions divide into evenly. Here’s how to find the LCM and LCD using the TI-84 Plus calculator:
Finding the Least Common Multiple (LCM) using TI-84 Plus
- Enter the numerators and denominators of the fractions into the calculator. For example, if you want to find the LCM of 1/2 and 1/3, enter 1/2 and 1/3 into the calculator.
- Press the “2nd” button, then press the “x-1” button to access the “lcm()” function.
- Type the fractions you entered in Step 1 as arguments to the “lcm()” function, separating them with a comma. For example, type lcm(1/2, 1/3).
- Press the “enter” button.
- The calculator will display the LCM of the fractions.
Finding the Least Common Denominator (LCD) using TI-84 Plus
- Enter the numerators and denominators of the fractions into the calculator. For example, if you want to find the LCD of 1/2 and 1/3, enter 1/2 and 1/3 into the calculator.
- Press the “2nd” button, then press the “x-1” button to access the “lcd()” function.
- Type the fractions you entered in Step 1 as arguments to the “lcd()” function, separating them with a comma. For example, type lcd(1/2, 1/3).
- Press the “enter” button.
- The calculator will display the LCD of the fractions.
Example
Find the LCM and LCD of 1/2, 1/3, and 1/4.
LCM:
- Enter 1/2, 1/3, and 1/4 into the calculator.
- Press the “2nd” button, then press the “x-1” button to access the “lcm()” function.
- Type lcm(1/2, 1/3, 1/4) into the calculator.
- Press the “enter” button.
- The calculator displays 6, which is the LCM of 1/2, 1/3, and 1/4.
LCD:
- Enter 1/2, 1/3, and 1/4 into the calculator.
- Press the “2nd” button, then press the “x-1” button to access the “lcd()” function.
- Type lcd(1/2, 1/3, 1/4) into the calculator.
- Press the “enter” button.
- The calculator displays 12, which is the LCD of 1/2, 1/3, and 1/4.
Additional Examples
Fraction 1 | Fraction 2 | LCM | LCD |
---|---|---|---|
1/2 | 1/3 | 6 | 6 |
1/3 | 1/4 | 12 | 12 |
1/4 | 1/5 | 20 | 20 |
1/2 | 1/3 | 1/4 | 12 |
Comparing and Ordering Fractions
To compare and order fractions on the TI-84 Plus calculator, follow these steps:
- Enter the first fraction into the calculator.
- Press the “>” key.
- Enter the second fraction.
- Press the “ENTER” key.
The calculator will display “1” if the first fraction is greater than the second fraction, “0” if the first fraction is less than the second fraction, or “ERROR” if the fractions are equal.
You can also use the “>” and “<” keys to compare and order fractions in a list.
- Enter the fractions into the calculator in a list.
- Press the “STAT” key.
- Select the “EDIT” menu.
- Select the “Sort” submenu.
- Select the “Ascending” or “Descending” option.
- Press the “ENTER” key.
The calculator will sort the fractions in ascending or descending order.
Converting Fractions to Decimals
To convert a fraction to a decimal on the TI-84 Plus calculator, follow these steps:
- Enter the fraction into the calculator.
- Press the “MATH” key.
- Select the “FRAC” menu.
- Select the “Dec” submenu.
- Press the “ENTER” key.
The calculator will display the decimal representation of the fraction.
Converting Decimals to Fractions
To convert a decimal to a fraction on the TI-84 Plus calculator, follow these steps:
- Enter the decimal into the calculator.
- Press the “MATH” key.
- Select the “FRAC” menu.
- Select the “Frac” submenu.
- Press the “ENTER” key.
The calculator will display the fraction representation of the decimal.
Adding and Subtracting Fractions
To add or subtract fractions on the TI-84 Plus calculator, follow these steps:
- Enter the first fraction into the calculator.
- Press the “+” or “-” key.
- Enter the second fraction.
- Press the “ENTER” key.
The calculator will display the sum or difference of the fractions.
Multiplying and Dividing Fractions
To multiply or divide fractions on the TI-84 Plus calculator, follow these steps:
- Enter the first fraction into the calculator.
- Press the “*” or “/” key.
- Enter the second fraction.
- Press the “ENTER” key.
The calculator will display the product or quotient of the fractions.
Simplifying Fractions
To simplify a fraction on the TI-84 Plus calculator, follow these steps:
- Enter the fraction into the calculator.
- Press the “MATH” key.
- Select the “FRAC” menu.
- Select the “Simp” submenu.
- Press the “ENTER” key.
The calculator will display the simplified fraction.
Using Fractions in Equations
You can use fractions in equations on the TI-84 Plus calculator. For example, to solve the equation 1/2x + 1/4 = 1/8, you would enter the following into the calculator:
1/2x + 1/4 = 1/8 solve(1/2x + 1/4 = 1/8, x)
The calculator would display the solution x = 1/2.
Fraction | Decimal | Simplified Fraction |
---|---|---|
1/2 | 0.5 | 1/2 |
1/4 | 0.25 | 1/4 |
1/8 | 0.125 | 1/8 |
3/4 | 0.75 | 3/4 |
5/8 | 0.625 | 5/8 |
Solving Equations Involving Fractions
Here’s a step-by-step guide on how to solve equations involving fractions on the TI-84 Plus calculator:
1. Simplify the equation
Start by simplifying the equation as much as possible. This may involve multiplying or dividing both sides by the same number to get rid of fractions, or combining like terms.
2. Multiply both sides by the LCD
The least common denominator (LCD) of the fractions in the equation is the smallest number that is divisible by all of the denominators. Multiply both sides of the equation by the LCD to get rid of the fractions.
3. Solve the resulting equation
Once you have multiplied both sides by the LCD, you will have a new equation that no longer contains fractions. Solve this equation using the usual methods for solving equations.
4. Check your solution
Once you have found a solution to the equation, check your solution by plugging it back into the original equation. If the equation holds true, then your solution is correct.
Example:
Solve the equation 1/2x + 1/4 = 1/3.
1. Simplify the equation
12(1/2x + 1/4) = 12(1/3)
6x + 3 = 4
2. Multiply both sides by the LCD
6x = 1
3. Solve the resulting equation
x = 1/6
4. Check your solution
1/2(1/6) + 1/4 = 1/3
1/12 + 1/4 = 1/3
4/12 + 3/12 = 1/3
7/12 = 1/3
Additional Tips
– When multiplying fractions, multiply the numerators and multiply the denominators.
– When dividing fractions, invert the second fraction and multiply.
– The LCD can be found by finding the least common multiple (LCM) of the denominators.
– Be careful not to divide by zero.
Using Fractions to Solve Word Problems
Fractions are a common part of everyday life. We use them to describe portions of food, time, and distance. When solving word problems involving fractions, it is important to understand the concepts of numerators, denominators, and equivalent fractions.
Numerators represent the number of parts being considered, while denominators represent the total number of parts into which a whole is divided. Equivalent fractions are fractions that represent the same value, even though they have different numerators and denominators.
For example, the fractions 1/2, 2/4, and 3/6 are all equivalent because they represent the same value, which is half of a whole.
When solving word problems involving fractions, follow these steps:
- Read the problem carefully. Determine what information is being provided and what information is being asked for.
- Identify the fractions in the problem. Determine the numerators and denominators of each fraction.
- Convert any mixed numbers to improper fractions. A mixed number is a number that has a whole number part and a fraction part. To convert a mixed number to an improper fraction, multiply the whole number part by the denominator of the fraction part and then add the numerator of the fraction part. The result is the numerator of the improper fraction, and the denominator is the same as the denominator of the original fraction.
- Find the least common multiple (LCM) of the denominators. The LCM is the smallest number that is divisible by all of the denominators. To find the LCM, list the prime factors of each denominator and then multiply the highest power of each prime factor that appears in any of the denominators.
- Convert all the fractions to equivalent fractions with the LCM as the denominator. To do this, multiply the numerator and denominator of each fraction by the appropriate factor.
- Perform the operation(s) indicated by the problem. This may involve adding, subtracting, multiplying, or dividing fractions.
- Simplify the result. Reduce the fraction to its lowest terms by dividing the numerator and denominator by their greatest common factor (GCF). Express the result as a mixed number if appropriate.
Example:
A recipe for chocolate chip cookies calls for 2 1/2 cups of flour. If you only have 3/4 of a cup of flour, what fraction of the recipe can you make?
Solution:
- Read the problem carefully. You are given that you have 3/4 of a cup of flour and you need to determine what fraction of the recipe you can make.
- Identify the fractions in the problem. The fraction 2 1/2 is equivalent to the improper fraction 5/2, and the fraction 3/4 is equivalent to the improper fraction 3/4.
- Convert the mixed number to an improper fraction. 5/2
- Find the least common multiple (LCM) of the denominators. The LCM of 2 and 4 is 4.
- Convert all the fractions to equivalent fractions with the LCM as the denominator. 5/2 x 2/2 = 10/4 and 3/4 x 1/1 = 3/4
- Perform the operation indicated by the problem. 10/4 – 3/4 = 7/4
- Simplify the result. 7/4
Therefore, you can make 7/4 of the recipe with 3/4 of a cup of flour.
Additional Tips:
- When adding or subtracting fractions, make sure the fractions have the same denominator.
- When multiplying fractions, multiply the numerators and multiply the denominators.
- When dividing fractions, invert the divisor and multiply.
- Don’t be afraid to use a calculator to check your answers.
Evaluating Numerical Expressions with Fractions
The TI-84 Plus calculator can be used to evaluate numerical expressions involving fractions. To do this, you can use the following steps:
- Enter the numerator of the fraction into the calculator.
- Press the “เธซเธฒเธฃ” (รท) key.
- Enter the denominator of the fraction into the calculator.
- Press the “ENTER” key.
For example, to evaluate the expression 1/2, you would enter the following into the calculator:
and press the “ENTER” key. The calculator would then display the result, which is 0.5.
Using the Ans Variable
You can also use the Ans variable to store the result of a previous calculation. This can be useful if you want to use the result of one calculation in a subsequent calculation.
To store the result of a calculation in the Ans variable, simply press the “STORE” key after the calculation is complete. For example, to store the result of the expression 1/2 in the Ans variable, you would enter the following into the calculator:
The Ans variable can then be used in subsequent calculations by simply entering its name. For example, to calculate the expression 1/2 + 1/4, you would enter the following into the calculator:
Using the Fraction Key
The TI-84 Plus calculator also has a dedicated fraction key, which can be used to enter fractions directly into the calculator.
To enter a fraction using the fraction key, press the “ALPHA” key followed by the “x-1” key. The calculator will then display a fraction template. Enter the numerator of the fraction into the top box and the denominator of the fraction into the bottom box. Press the “ENTER” key to enter the fraction into the calculator.
For example, to enter the fraction 1/2 into the calculator, you would press the following keys:
Evaluating More Complex Expressions
The TI-84 Plus calculator can also be used to evaluate more complex expressions involving fractions. For example, to evaluate the expression (1/2) + (1/4), you would enter the following into the calculator:
(
The calculator would then display the result, which is 3/4.
Table of Examples
Expression | Calculator Input | Result |
1/2 | 1 รท 2 | 0.5 |
1/2 + 1/4 | (1 รท 2) + (1 รท 4) | 0.75 |
(1/2) * (1/4) | (1 รท 2) * (1 รท 4) | 0.125 |
1/(1/2) | 1 รท (1 รท 2) | 2 |
Finding Critical Points of Functions Involving Fractions
Critical points are points where the first derivative of a function is either zero or undefined. To find the critical points of a function involving fractions, we can use the quotient rule.
The quotient rule states that if we have a function of the form $f(x) = \frac{p(x)}{q(x)}$, where $p(x)$ and $q(x)$ are polynomials, then the derivative of $f(x)$ is given by:
$$f'(x) = \frac{q(x)p'(x) – p(x)q'(x)}{q(x)^2}$$
Using this rule, we can find the critical points of any function involving fractions.
Example
Find the critical points of the function $f(x) = \frac{x^2+1}{x-1}$.
Using the quotient rule, we find that:
$$f'(x) = \frac{(x-1)(2x) – (x^2+1)(1)}{(x-1)^2} = \frac{2x^2 – 2x – x^2 – 1}{(x-1)^2} = \frac{x^2 – 2x – 1}{(x-1)^2}$$
The critical points are the points where $f'(x) = 0$ or $f'(x)$ is undefined.
To find where $f'(x) = 0$, we solve the equation $x^2 – 2x – 1 = 0$. This equation factors as $(x-1)(x+1) = 0$, so the solutions are $x = 1$ and $x = -1$.
To find where $f'(x)$ is undefined, we set the denominator of $f'(x)$ equal to zero. This gives us $(x-1)^2 = 0$, so the only solution is $x = 1$.
Therefore, the critical points of $f(x) = \frac{x^2+1}{x-1}$ are $x = 1$ and $x = -1$.
General Procedure
To find the critical points of a function involving fractions, we can follow these steps:
- Find the derivative of the function using the quotient rule.
- Set the derivative equal to zero and solve for $x$.
- Set the denominator of the derivative equal to zero and solve for $x$.
- The critical points are the points where the derivative is zero or undefined.
Additional Notes
* If the denominator of the function is a constant, then the function will not have any critical points.
* If the numerator of the function is a constant, then the function will have a critical point at $x = 0$.
* If the function is undefined at a point, then that point is not a critical point.
Using Derivatives to Analyze Functions with Fractions
The derivative of a function is a measure of its rate of change. It can be used to analyze the function’s behavior, including its critical points, maxima, and minima.
When dealing with functions that contain fractions, it is important to remember that the derivative of a quotient is equal to the numerator times the derivative of the denominator minus the denominator times the derivative of the numerator, all divided by the square of the denominator.
$$ \frac{d}{dx} \left[ \frac{f(x)}{g(x)} \right] = \frac{g(x)f'(x) – f(x)g'(x)}{g(x)^2} $$
This rule can be used to find the derivative of any function that contains a fraction. For example, the derivative of the function
$$ f(x) = \frac{x^2 + 1}{x-1} $$
is
$$ f'(x) = \frac{(x-1)(2x) – (x^2 + 1)(1)}{(x-1)^2} = \frac{2x^2 – 2x – x^2 – 1}{(x-1)^2} = \frac{x^2 – 2x – 1}{(x-1)^2} $$
This derivative can be used to analyze the function’s behavior. For example, the derivative is equal to zero at the points x = 1 and x = -1/2. These points are the critical points of the function.
The derivative is positive for x > 1 and x < -1/2. This means that the function is increasing on these intervals. The derivative is negative for -1/2 < x < 1. This means that the function is decreasing on this interval.
The function has a maximum at the point x = 1 and a minimum at the point x = -1/2. These points can be found by finding the critical points and then evaluating the function at these points.
The derivative can also be used to find the concavity of the function. The function is concave up on the intervals (-โ, -1/2) and (1, โ). The function is concave down on the interval (-1/2, 1).
The concavity of the function can be used to determine the function’s shape. A function that is concave up is a parabola that opens up. A function that is concave down is a parabola that opens down.
The derivative is a powerful tool that can be used to analyze the behavior of functions. When dealing with functions that contain fractions, it is important to remember the quotient rule for derivatives.
Example
Find the derivative of the function
$$ f(x) = \frac{x^3 + 2x^2 – 1}{x^2 – 1} $$
Using the quotient rule, we have
$$ f'(x) = \frac{(x^2 – 1)(3x^2 + 4x) – (x^3 + 2x^2 – 1)(2x)}{(x^2 – 1)^2} $$
$$ = \frac{3x^4 + 4x^3 – 3x^2 – 4x – 2x^4 – 4x^3 + 4x^2 + 2x}{(x^2 – 1)^2} $$
$$ = \frac{x^4}{(x^2 – 1)^2} $$
The derivative of the function is
$$ f'(x) = \frac{x^4}{(x^2 – 1)^2} $$
Using Integrals to Find the Area Under a Curve Involving Fractions
1. Define the Function
Begin by entering the function involving fractions into the TI-84 Plus. For instance, to enter the function f(x) = (x+2)/(x-1), press the following keys:
- MODE
- FUNC
- Y=
- Enter (x+2)/(x-1)
2. Set the Graph Window
Adjust the graph window to display the relevant portion of the curve. To do this, press the WINDOW button and enter appropriate values for Xmin, Xmax, Ymin, and Ymax.
For example, to set the window to display the curve from x=-5 to x=5 and y=-10 to y=10, enter the following values:
Setting | Value |
---|---|
Xmin | -5 |
Xmax | 5 |
Ymin | -10 |
Ymax | 10 |
3. Find the Roots of the Denominator
To prepare for integration, you need to find the roots of the denominator of the function. In this example, the denominator is x-1. Press the CALC button, select ZERO, then choose ZERO again. Use the arrow keys to move the cursor to the zero point of the function and press ENTER.
4. Use the Integration Feature
Once you have defined the function and set the appropriate window, you can use the integration feature to find the area under the curve. Press the MATH button, select NUMERICAL, and then choose โซf(x)dx.
5. Specify the Bounds of Integration
Enter the lower and upper bounds of integration. For instance, to find the area under the curve from x=0 to x=3, enter 0 as the lower bound and 3 as the upper bound.
6. Calculate the Integral
Press ENTER to calculate the integral value, which represents the area under the curve within the specified bounds.
7. Resolve Indeterminate Forms
If the integral result is an indeterminate form such as โ, -โ, or 0/0, you will need to investigate the behavior of the function near the point of discontinuity. Use limit evaluation techniques or graphing to determine the appropriate value.
17. Example: Finding the Area Under a Hyperbola
Let’s find the area under the hyperbola f(x) = (x-1)/(x+1) from x=0 to x=2 using the TI-84 Plus.
Steps:
- Enter the function: y1=(x-1)/(x+1)
- Set the graph window: Xmin=-5, Xmax=5, Ymin=-5, Ymax=5
- Find the root of the denominator: x=-1
- Integrate the function:
- MATH
- NUMERICAL
- โซf(x)dx
- 0, 2
- Result: ln(3) โ 1.0986
How to Calculate Limits of Functions with Fractions on TI-84 Plus
The TI-84 Plus calculator can be used to calculate limits of functions, including functions that contain fractions. To calculate the limit of a function with a fraction, follow these steps:
1. Enter the function into the calculator.
2. Press the “CALC” button.
3. Select the “limit” option.
4. Enter the value of the variable at which you want to calculate the limit.
5. Press the “ENTER” button.
The calculator will display the limit of the function at the given value of the variable.
For example, to calculate the limit of the function f(x) = (x^2 – 1) / (x – 1) at x = 1, follow these steps:
1. Enter the function into the calculator: f(x) = (x^2 – 1) / (x – 1)
2. Press the “CALC” button.
3. Select the “limit” option.
4. Enter the value of x at which you want to calculate the limit: x = 1
5. Press the “ENTER” button.
The calculator will display the limit of the function at x = 1, which is 2.
Example: Calculating the Limit of a Rational Function
Consider the rational function:
“`
f(x) = (x^2 – 4) / (x – 2)
“`
To find the limit of this function as x approaches 2, we can use the TI-84 Plus calculator.
Step 1: Enter the function into the calculator.
“`
f(x) = (x^2 – 4) / (x – 2)
“`
Step 2: Press the “CALC” button.
Step 3: Select the “limit” option.
Step 4: Enter the value of x at which you want to calculate the limit.
“`
x = 2
“`
Step 5: Press the “ENTER” button.
The calculator will display the limit of the function as x approaches 2, which is 4.
Input | Output |
---|---|
f(x) = (x^2 – 4) / (x – 2) | 4 |
Additional Notes
When calculating limits of functions with fractions, it is important to note the following:
* The limit of a fraction is equal to the limit of the numerator divided by the limit of the denominator, provided that the denominator does not approach zero.
* If the denominator of a fraction approaches zero, the limit of the fraction may be indeterminate. In this case, you may need to use other techniques to evaluate the limit.
* It is always a good idea to simplify fractions before calculating limits. This can help to avoid potential errors.
Handling Continuity of Functions with Fractions
Manipulating fractions on the TI-84 Plus calculator empowers us to explore the behavior of functions containing fractions and assess their continuity. Functions carrying fractions may possess discontinuities, points where the function experiences abrupt interruptions or “jumps.” These discontinuities can arise due to the particular nature of the fraction, such as division by zero or undefined expressions.
To determine the continuity of a function involving fractions, we must scrutinize the function’s behavior at critical points where the denominator of the fraction approaches zero or becomes undefined. If the function’s limit at that point coincides with the function’s value at that point, then the function is considered continuous at that point. Otherwise, a discontinuity exists.
Removable Discontinuities
In certain cases, discontinuities can be “removed” by simplifying or redefining the function. For instance, consider the function:
f(x) = (x-2)/(x^2-4)
The denominator, (x^2-4), approaches zero at x = 2 and x = -2. However, these points are not removable discontinuities because the limit of the function as x approaches either of these points does not match the function’s value at those points.
Point | Limit | Function Value | Discontinuity Type |
---|---|---|---|
x = 2 | 1/4 | Undefined | Essential Discontinuity |
x = -2 | -1/4 | Undefined | Essential Discontinuity |
Essential Discontinuities: Points where the limit of the function does not exist or is infinite, making the discontinuity “essential” or irremovable.
Example: Identifying Discontinuities
Let’s examine the function:
g(x) = (x^2-9)/(x-3)
The denominator, (x-3), approaches zero at x = 3. Substituting x = 3 into the function yields an undefined expression, indicating a potential discontinuity.
To determine the type of discontinuity, we calculate the limit of the function as x approaches 3:
lim (x->3) (x^2-9)/(x-3) = lim (x->3) [(x+3)(x-3)]/(x-3) = lim (x->3) x+3 = 6
Since the limit (6) does not coincide with the function’s value at x = 3 (undefined), the discontinuity is essential and cannot be removed.
Summary of Continuity Conditions
To determine the continuity of a function involving fractions:
1. Factor the denominator to identify potential discontinuities.
2. Substitute the potential discontinuity into the function to check for an undefined expression.
3. If an undefined expression is found, calculate the limit of the function as x approaches the potential discontinuity.
4. If the limit exists and equals the function’s value at that point, the discontinuity is removable.
5. If the limit does not exist or does not equal the function’s value at that point, the discontinuity is essential.
Derivatives of Functions with Fractions
The derivative of a fraction is found using the quotient rule, which states that the derivative of is given by:
Where and represent the derivatives of and , respectively.
22. Example
Find the derivative of .
Solution:
Using the quotient rule, we have:
Therefore, .
The following table provides additional examples of derivatives of functions with fractions:
Function |
Derivative |
||||||||||||||||||||||||||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Integrals of Fractions: Partial Fraction DecompositionIn order to find the indefinite integral of a fraction, we can use a technique called partial fraction decomposition. This involves breaking down the fraction into simpler fractions that can be integrated more easily. For example, consider the following fraction: $$\frac{x^2+2x+1}{x^2-1}$$ We can factor the denominator as: $$x^2-1=(x+1)(x-1)$$ So, we can decompose the fraction as follows: $$\frac{x^2+2x+1}{x^2-1}=\frac{A}{x+1}+\frac{B}{x-1}$$ where A and B are constants that we need to solve for. To find A, we multiply both sides of the equation by x+1: $$x^2+2x+1=A(x-1)+B(x+1)$$ Setting x=-1, we get: $$1=2A\Rightarrow A=\frac{1}{2}$$ To find B, we multiply both sides of the equation by x-1: $$x^2+2x+1=A(x-1)+B(x+1)$$ Setting x=1, we get: $$3=2B\Rightarrow B=\frac{3}{2}$$ Therefore, we have: $$\frac{x^2+2x+1}{x^2-1}=\frac{1}{2(x+1)}+\frac{3}{2(x-1)}$$ Now, we can integrate each of these fractions separately: $$\int\frac{x^2+2x+1}{x^2-1}dx=\frac{1}{2}\int\frac{1}{x+1}dx+\frac{3}{2}\int\frac{1}{x-1}dx$$ Using the power rule of integration, we get: $$\int\frac{x^2+2x+1}{x^2-1}dx=\frac{1}{2}\ln|x+1|+\frac{3}{2}\ln|x-1|+C$$ where C is the constant of integration. Integration by SubstitutionAnother method that can be used to find the indefinite integral of a fraction is integration by substitution. This involves making a substitution for a part of the integrand that results in a simpler expression. For example, consider the following fraction: $$\frac{1}{x^2+1}$$ We can make the substitution u=x^2+1, which gives us: $$du=2xdx$$ Substituting into the integral, we get: $$\int\frac{1}{x^2+1}dx=\frac{1}{2}\int\frac{1}{u}du$$ Now, we can use the power rule of integration to get: $$\int\frac{1}{x^2+1}dx=\frac{1}{2}\ln|u|+C$$ Substituting back for u, we get: $$\int\frac{1}{x^2+1}dx=\frac{1}{2}\ln|x^2+1|+C$$ where C is the constant of integration. Integration by PartsIntegration by parts is a technique that can be used to find the indefinite integral of a product of two functions. This involves finding two functions, u and dv, such that: $$du=v’dx\qquad\text{and}\qquad dv=udx$$ and then integrating by parts using the following formula: $$\int udv=uv-\int vdu$$ For example, consider the following fraction: $$\frac{x}{x^2+1}$$ We can choose u=x and dv=1/(x^2+1)dx, which gives us: $$du=dx\qquad\text{and}\qquad dv=\frac{1}{x^2+1}dx$$ Substituting into the formula for integration by parts, we get: $$\int\frac{x}{x^2+1}dx=x\frac{1}{x^2+1}-\int\frac{1}{x^2+1}dx$$ Now, we can use the power rule of integration to get: $$\int\frac{x}{x^2+1}dx=x\frac{1}{x^2+1}-\tan^{-1}x+C$$ where C is the constant of integration. ExamplesHere are some examples of how to find the indefinite integral of a fraction using the various techniques discussed above:
|