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Mastering Rational Expressions: A Comprehensive Guide

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Priscila Garcia

11/16/2025

Arithmetic

Rational Expressions

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Nov 16, 2025

4 pages

Mastering Rational Expressions: A Comprehensive Guide

user profile picture

Priscila Garcia

@priscilagarcia_etnz

Rational expressions are fractions containing polynomials in both the numerator... Show more

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Rational
Expressions
What is a rational expression?
A rational expression is an expression that can be written as a
ratio (fraction) of two

Understanding Rational Expressions

A rational expression is simply a fraction where both the top (numerator) and bottom (denominator) are polynomials. Examples include x+34\frac{x+3}{4}, x2+2x5x+1\frac{x^2 + 2x - 5}{x+1}, and x27x+12x2+4x12\frac{x^2 - 7x + 12}{x^2 + 4x - 12}.

When simplifying rational expressions, remember that only factors can be simplified. Factors are parts that are multiplied together to make a product. You can simplify by dividing common factors that appear in both the numerator and denominator.

💡 Think of simplifying rational expressions like canceling in regular fractions. Just as 68=3242=34\frac{6}{8} = \frac{3 \cdot 2}{4 \cdot 2} = \frac{3}{4}, you can simplify expressions by identifying common factors.

Rational
Expressions
What is a rational expression?
A rational expression is an expression that can be written as a
ratio (fraction) of two

Simplifying Rational Expressions

Look at this example: (x5)(x+3)x(x5)=x+3x\frac{(x - 5)(x + 3)}{x (x - 5)} = \frac{x + 3}{x} because (x5)(x5)=1\frac{(x - 5)}{(x - 5)} = 1. The factors in the numerator are (x5)(x - 5) and (x+3)(x + 3), while the denominator has factors of xx and (x5)(x - 5).

A common mistake is trying to "cancel" terms that are added or subtracted. Only factors (terms multiplied together) can be simplified! For example, x27x+12x2+x127x+12x12\frac{x^2 - 7x + 12}{x^2 + x - 12} \neq \frac{-7x + 12}{x - 12} because x2x^2 is not a factor - it's being added to other terms.

Remember that terms separated by addition or subtraction cannot be divided when simplifying. You need to factor the expressions first to find common factors.

⚠️ Never try to cancel terms connected by addition or subtraction! This is one of the most common errors students make with rational expressions.

Rational
Expressions
What is a rational expression?
A rational expression is an expression that can be written as a
ratio (fraction) of two

Factoring to Simplify

To correctly simplify expressions like x27x+12x2+x12\frac{x^2 - 7x + 12}{x^2 + x - 12}, you must factor both polynomials completely first. Let's see the proper approach:

x27x+12x2+x12=(x4)(x3)(x+4)(x3)=x4x+4\frac{x^2 - 7x + 12}{x^2 + x - 12} = \frac{(x-4)(x-3)}{(x+4)(x-3)} = \frac{x-4}{x+4}

Notice how we factored both the numerator and denominator, then identified the common factor of (x3)(x-3) which cancels out. This gives us the simplified expression.

When multiplying rational expressions, follow these steps: break expressions into factor form, cancel common factors between numerator and denominator, then multiply the remaining terms.

💡 Factoring is your best friend when working with rational expressions. It reveals common factors that can be simplified and makes complex problems much easier!

Rational
Expressions
What is a rational expression?
A rational expression is an expression that can be written as a
ratio (fraction) of two

Dividing Rational Expressions

Division with rational expressions is straightforward once you know the trick: change division to multiplication by taking the reciprocal (flip) of the second fraction.

For example, to solve x3x3x÷2x+6x\frac{x - 3x}{3x} \div \frac{2x + 6}{x}, convert it to: x3x3xx2x+6\frac{x - 3x}{3x} \cdot \frac{x}{2x + 6}

After converting to multiplication, you can factor, simplify common factors, and multiply the remaining terms just like in the previous examples.

🔑 Remember this simple rule: when dividing by a fraction, multiply by its reciprocal. This works for all fractions, including rational expressions!



We thought you’d never ask...

What is the Knowunity AI companion?

Our AI companion is specifically built for the needs of students. Based on the millions of content pieces we have on the platform we can provide truly meaningful and relevant answers to students. But its not only about answers, the companion is even more about guiding students through their daily learning challenges, with personalised study plans, quizzes or content pieces in the chat and 100% personalisation based on the students skills and developments.

Where can I download the Knowunity app?

You can download the app in the Google Play Store and in the Apple App Store.

Is Knowunity really free of charge?

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The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.

Stefan S

iOS user

This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.

Samantha Klich

Android user

Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.

Anna

iOS user

I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️

Thomas R

iOS user

Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades

Brad T

Android user

Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍

David K

iOS user

The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!

Sudenaz Ocak

Android user

In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.

Greenlight Bonnie

Android user

I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend

Aubrey

iOS user

Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀

Marco B

iOS user

THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮

Elisha

iOS user

This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!

Paul T

iOS user

The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.

Stefan S

iOS user

This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.

Samantha Klich

Android user

Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.

Anna

iOS user

I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️

Thomas R

iOS user

Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades

Brad T

Android user

Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍

David K

iOS user

The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!

Sudenaz Ocak

Android user

In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.

Greenlight Bonnie

Android user

I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend

Aubrey

iOS user

Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀

Marco B

iOS user

THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮

Elisha

iOS user

This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!

Paul T

iOS user

 

Arithmetic

296

Nov 16, 2025

4 pages

Mastering Rational Expressions: A Comprehensive Guide

user profile picture

Priscila Garcia

@priscilagarcia_etnz

Rational expressions are fractions containing polynomials in both the numerator and denominator. Mastering these expressions helps you solve complex algebra problems and prepares you for more advanced math topics like calculus.

Rational
Expressions
What is a rational expression?
A rational expression is an expression that can be written as a
ratio (fraction) of two

Sign up to see the contentIt's free!

Access to all documents

Improve your grades

Join milions of students

By signing up you accept Terms of Service and Privacy Policy

Understanding Rational Expressions

A rational expression is simply a fraction where both the top (numerator) and bottom (denominator) are polynomials. Examples include x+34\frac{x+3}{4}, x2+2x5x+1\frac{x^2 + 2x - 5}{x+1}, and x27x+12x2+4x12\frac{x^2 - 7x + 12}{x^2 + 4x - 12}.

When simplifying rational expressions, remember that only factors can be simplified. Factors are parts that are multiplied together to make a product. You can simplify by dividing common factors that appear in both the numerator and denominator.

💡 Think of simplifying rational expressions like canceling in regular fractions. Just as 68=3242=34\frac{6}{8} = \frac{3 \cdot 2}{4 \cdot 2} = \frac{3}{4}, you can simplify expressions by identifying common factors.

Rational
Expressions
What is a rational expression?
A rational expression is an expression that can be written as a
ratio (fraction) of two

Sign up to see the contentIt's free!

Access to all documents

Improve your grades

Join milions of students

By signing up you accept Terms of Service and Privacy Policy

Simplifying Rational Expressions

Look at this example: (x5)(x+3)x(x5)=x+3x\frac{(x - 5)(x + 3)}{x (x - 5)} = \frac{x + 3}{x} because (x5)(x5)=1\frac{(x - 5)}{(x - 5)} = 1. The factors in the numerator are (x5)(x - 5) and (x+3)(x + 3), while the denominator has factors of xx and (x5)(x - 5).

A common mistake is trying to "cancel" terms that are added or subtracted. Only factors (terms multiplied together) can be simplified! For example, x27x+12x2+x127x+12x12\frac{x^2 - 7x + 12}{x^2 + x - 12} \neq \frac{-7x + 12}{x - 12} because x2x^2 is not a factor - it's being added to other terms.

Remember that terms separated by addition or subtraction cannot be divided when simplifying. You need to factor the expressions first to find common factors.

⚠️ Never try to cancel terms connected by addition or subtraction! This is one of the most common errors students make with rational expressions.

Rational
Expressions
What is a rational expression?
A rational expression is an expression that can be written as a
ratio (fraction) of two

Sign up to see the contentIt's free!

Access to all documents

Improve your grades

Join milions of students

By signing up you accept Terms of Service and Privacy Policy

Factoring to Simplify

To correctly simplify expressions like x27x+12x2+x12\frac{x^2 - 7x + 12}{x^2 + x - 12}, you must factor both polynomials completely first. Let's see the proper approach:

x27x+12x2+x12=(x4)(x3)(x+4)(x3)=x4x+4\frac{x^2 - 7x + 12}{x^2 + x - 12} = \frac{(x-4)(x-3)}{(x+4)(x-3)} = \frac{x-4}{x+4}

Notice how we factored both the numerator and denominator, then identified the common factor of (x3)(x-3) which cancels out. This gives us the simplified expression.

When multiplying rational expressions, follow these steps: break expressions into factor form, cancel common factors between numerator and denominator, then multiply the remaining terms.

💡 Factoring is your best friend when working with rational expressions. It reveals common factors that can be simplified and makes complex problems much easier!

Rational
Expressions
What is a rational expression?
A rational expression is an expression that can be written as a
ratio (fraction) of two

Sign up to see the contentIt's free!

Access to all documents

Improve your grades

Join milions of students

By signing up you accept Terms of Service and Privacy Policy

Dividing Rational Expressions

Division with rational expressions is straightforward once you know the trick: change division to multiplication by taking the reciprocal (flip) of the second fraction.

For example, to solve x3x3x÷2x+6x\frac{x - 3x}{3x} \div \frac{2x + 6}{x}, convert it to: x3x3xx2x+6\frac{x - 3x}{3x} \cdot \frac{x}{2x + 6}

After converting to multiplication, you can factor, simplify common factors, and multiply the remaining terms just like in the previous examples.

🔑 Remember this simple rule: when dividing by a fraction, multiply by its reciprocal. This works for all fractions, including rational expressions!

We thought you’d never ask...

What is the Knowunity AI companion?

Our AI companion is specifically built for the needs of students. Based on the millions of content pieces we have on the platform we can provide truly meaningful and relevant answers to students. But its not only about answers, the companion is even more about guiding students through their daily learning challenges, with personalised study plans, quizzes or content pieces in the chat and 100% personalisation based on the students skills and developments.

Where can I download the Knowunity app?

You can download the app in the Google Play Store and in the Apple App Store.

Is Knowunity really free of charge?

That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.

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4.9/5

App Store

4.8/5

Google Play

The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.

Stefan S

iOS user

This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.

Samantha Klich

Android user

Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.

Anna

iOS user

I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️

Thomas R

iOS user

Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades

Brad T

Android user

Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍

David K

iOS user

The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!

Sudenaz Ocak

Android user

In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.

Greenlight Bonnie

Android user

I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend

Aubrey

iOS user

Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀

Marco B

iOS user

THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮

Elisha

iOS user

This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!

Paul T

iOS user

The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.

Stefan S

iOS user

This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.

Samantha Klich

Android user

Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.

Anna

iOS user

I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️

Thomas R

iOS user

Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades

Brad T

Android user

Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍

David K

iOS user

The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!

Sudenaz Ocak

Android user

In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.

Greenlight Bonnie

Android user

I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend

Aubrey

iOS user

Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀

Marco B

iOS user

THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮

Elisha

iOS user

This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!

Paul T

iOS user