# [Help] Multiplying and Dividing Rational Expressions

• May 21st 2009, 02:46 PM
JosephLive93
[Help] Multiplying and Dividing Rational Expressions
Alright, I wanted to check and see if I got my answer right to this following question..

http://img42.imageshack.us/img42/4852/hellppp.jpg

I came up with x over 3x+4

Thanks (Wink)
• May 21st 2009, 02:55 PM
mathswend
Factorise both fractions to get

(x+4)(x-4)/(x-4) X x/3(x+4)

I then simplified to get x/3
• May 21st 2009, 04:11 PM
pickslides
$\displaystyle \frac{x^2-16}{x-4} \div \frac{3x+12}{x}$

change divide into times by flipping the second term

$\displaystyle \frac{x^2-16}{x-4} \times \frac{x}{3x+12}$

now factor the top of the first term using difference of 2 squares and the bottom of the second term by taking out a common factor

$\displaystyle \frac{(x-4)(x+4)}{x-4} \times \frac{x}{3(x+4)}$

now times the 2 terms together you get

$\displaystyle \frac{(x-4)(x+4)x}{3(x+4)(x-4)}$

and cancelling out terms

$\displaystyle \frac{x}{3}$