<< Chapter < Page Chapter >> Page >
By the end of this section, you will be able to:
  • Multiply rational expressions
  • Divide rational expressions

Before you get started, take this readiness quiz.

If you miss a problem, go back to the section listed and review the material.

  1. Multiply: 14 15 · 6 35 .
    If you missed this problem, review [link] .
  2. Divide: 14 15 ÷ 6 35 .
    If you missed this problem, review [link] .
  3. Factor completely: 2 x 2 98 .
    If you missed this problem, review [link] .
  4. Factor completely: 10 n 3 + 10 .
    If you missed this problem, review [link] .
  5. Factor completely: 10 p 2 25 p q 15 q 2 .
    If you missed this problem, review [link] .

Multiply rational expressions

To multiply rational expressions, we do just what we did with numerical fractions. We multiply the numerators and multiply the denominators. Then, if there are any common factors, we remove them to simplify the result.

Multiplication of rational expressions

If p , q , r , s are polynomials where q 0 and s 0 , then

p q · r s = p r q s

To multiply rational expressions, multiply the numerators and multiply the denominators.

We’ll do the first example with numerical fractions to remind us of how we multiplied fractions without variables.

Multiply: 10 28 · 8 15 .

Solution

.
Multiply the numerators and denominators. .
Look for common factors, and then remove them. .
Simplify. .

Got questions? Get instant answers now!
Got questions? Get instant answers now!

Mulitply: 6 10 · 15 12 .

3 4

Got questions? Get instant answers now!

Mulitply: 20 15 · 6 8 .

1

Got questions? Get instant answers now!

Remember, throughout this chapter, we will assume that all numerical values that would make the denominator be zero are excluded. We will not write the restrictions for each rational expression, but keep in mind that the denominator can never be zero. So in this next example, x 0 and y 0 .

Mulitply: 2 x 3 y 2 · 6 x y 3 x 2 y .

Solution

.
Multiply. .
Factor the numerator and denominator completely, and then remove common factors. .
Simplify. .

Got questions? Get instant answers now!
Got questions? Get instant answers now!

Mulitply: 3 p q q 2 · 5 p 2 q 6 p q .

5 p 2 q

Got questions? Get instant answers now!

Mulitply: 6 x 3 y 7 x 2 · 2 x y 3 x 2 y .

12 y 3 7

Got questions? Get instant answers now!

How to multiply rational expressions

Mulitply: 2 x x 2 + x + 12 · x 2 9 6 x 2 .

Solution

The above image has three columns and three rows to show how to multiply rational expressions. Step one is to factor each numerator and denominator completely. Factor x squared minus 9 and x squared plus x plus 12. The rational equation is 2x divided by x squared plus x plus 12 times x squared minus 9 divided by 6x squared, then to 2x divided by x minus 3 times x minus 4 times x minus 3 times x plus 3 divided by 6x squared. Step 2 is to multiply the numerators and denominators. It is helpful to multiply the monomials first. Multiply 2x times x minus 3 times x plus 3 divided by 6x squared times x minus 3 times x minus 4. Step 3 is to divide out the common factors, canceling out 2, x, and x minus 3 in the numerator and 2, x and x minus 3 in the denominator. Leave the denominator in factored form to get x plus 3 divided by 3x times x minus 4.
Got questions? Get instant answers now!
Got questions? Get instant answers now!

Mulitply: 5 x x 2 + 5 x + 6 · x 2 4 10 x .

x 2 2 ( x + 3 )

Got questions? Get instant answers now!

Mulitply: 9 x 2 x 2 + 11 x + 30 · x 2 36 3 x 2 .

3 ( x 6 ) x + 5

Got questions? Get instant answers now!

Multiply a rational expression.

  1. Factor each numerator and denominator completely.
  2. Multiply the numerators and denominators.
  3. Simplify by dividing out common factors.

Multiply: n 2 7 n n 2 + 2 n + 1 · n + 1 2 n .

Solution

n 2 7 n n 2 + 2 n + 1 · n + 1 2 n Factor each numerator and denominator. n ( n 7 ) ( n + 1 ) ( n + 1 ) · n + 1 2 n Multiply the numerators and the denominators. n ( n 7 ) ( n + 1 ) ( n + 1 ) ( n + 1 ) 2 n Remove common factors. n ( n 7 ) ( n + 1 ) ( n + 1 ) ( n + 1 ) 2 n Simplify. n 7 2 ( n + 1 )

Got questions? Get instant answers now!
Got questions? Get instant answers now!

Multiply: x 2 25 x 2 3 x 10 · x + 2 x .

x + 5 x

Got questions? Get instant answers now!

Multiply: x 2 4 x x 2 + 5 x + 6 · x + 2 x .

x 4 x + 3

Got questions? Get instant answers now!

Multiply: 16 4 x 2 x 12 · x 2 5 x 6 x 2 16 .

Solution

16 4 x 2 x 12 · x 2 5 x 6 x 2 16 Factor each numerator and denominator. 4 ( 4 x ) 2 ( x 6 ) · ( x 6 ) ( x + 1 ) ( x 4 ) ( x + 4 ) Multiply the numerators and the denominators. 4 ( 4 x ) ( x 6 ) ( x + 1 ) 2 ( x 6 ) ( x 4 ) ( x + 4 ) Remove common factors. ( −1 ) 2 · 2 ( 4 x ) ( x 6 ) ( x + 1 ) 2 ( x 6 ) ( x 4 ) ( x + 4 ) Simplify. 2 ( x + 1 ) ( x + 4 )

Got questions? Get instant answers now!
Got questions? Get instant answers now!

Multiply: 12 x 6 x 2 x 2 + 8 x · x 2 + 11 x + 24 x 2 4 .

6 ( x + 3 ) x + 2

Got questions? Get instant answers now!

Multiply: 9 v 3 v 2 9 v + 36 · v 2 + 7 v + 12 v 2 9 .

v 3

Got questions? Get instant answers now!

Multiply: 2 x 6 x 2 8 x + 15 · x 2 25 2 x + 10 .

Solution

.
Factor each numerator and denominator. .
Multiply the numerators and denominators. .
Remove common factors. .
Simplify. .

Got questions? Get instant answers now!
Got questions? Get instant answers now!

Multiply: 3 a 21 a 2 9 a + 14 · a 2 4 3 a + 6 .

1

Got questions? Get instant answers now!

Multiply: b 2 b b 2 + 9 b 10 · b 2 100 b 2 10 b .

1

Got questions? Get instant answers now!

Divide rational expressions

To divide rational expressions we multiply the first fraction by the reciprocal of the second, just like we did for numerical fractions.

Questions & Answers

prostaglandin and fever
Maha Reply
Discuss the differences between taste and flavor, including how other sensory inputs contribute to our  perception of flavor.
John Reply
taste refers to your understanding of the flavor . while flavor one The other hand is refers to sort of just a blend things.
Faith
While taste primarily relies on our taste buds, flavor involves a complex interplay between taste and aroma
Kamara
which drugs can we use for ulcers
Ummi Reply
omeprazole
Kamara
what
Renee
what is this
Renee
is a drug
Kamara
of anti-ulcer
Kamara
Omeprazole Cimetidine / Tagament For the complicated once ulcer - kit
Patrick
what is the function of lymphatic system
Nency Reply
Not really sure
Eli
to drain extracellular fluid all over the body.
asegid
The lymphatic system plays several crucial roles in the human body, functioning as a key component of the immune system and contributing to the maintenance of fluid balance. Its main functions include: 1. Immune Response: The lymphatic system produces and transports lymphocytes, which are a type of
asegid
to transport fluids fats proteins and lymphocytes to the blood stream as lymph
Adama
what is anatomy
Oyindarmola Reply
Anatomy is the identification and description of the structures of living things
Kamara
what's the difference between anatomy and physiology
Oyerinde Reply
Anatomy is the study of the structure of the body, while physiology is the study of the function of the body. Anatomy looks at the body's organs and systems, while physiology looks at how those organs and systems work together to keep the body functioning.
AI-Robot
what is enzymes all about?
Mohammed Reply
Enzymes are proteins that help speed up chemical reactions in our bodies. Enzymes are essential for digestion, liver function and much more. Too much or too little of a certain enzyme can cause health problems
Kamara
yes
Prince
how does the stomach protect itself from the damaging effects of HCl
Wulku Reply
little girl okay how does the stomach protect itself from the damaging effect of HCL
Wulku
it is because of the enzyme that the stomach produce that help the stomach from the damaging effect of HCL
Kamara
function of digestive system
Ali Reply
function of digestive
Ali
the diagram of the lungs
Adaeze Reply
what is the normal body temperature
Diya Reply
37 degrees selcius
Xolo
37°c
Stephanie
please why 37 degree selcius normal temperature
Mark
36.5
Simon
37°c
Iyogho
the normal temperature is 37°c or 98.6 °Fahrenheit is important for maintaining the homeostasis in the body the body regular this temperature through the process called thermoregulation which involves brain skin muscle and other organ working together to maintain stable internal temperature
Stephanie
37A c
Wulku
what is anaemia
Diya Reply
anaemia is the decrease in RBC count hemoglobin count and PVC count
Eniola
what is the pH of the vagina
Diya Reply
how does Lysin attack pathogens
Diya
acid
Mary
I information on anatomy position and digestive system and there enzyme
Elisha Reply
anatomy of the female external genitalia
Muhammad Reply
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get Jobilize Job Search Mobile App in your pocket Now!

Get it on Google Play Download on the App Store Now




Source:  OpenStax, Elementary algebra. OpenStax CNX. Jan 18, 2017 Download for free at http://cnx.org/content/col12116/1.2
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Elementary algebra' conversation and receive update notifications?

Ask