# Math Help - Dividing Rational expressions

1. ## Dividing Rational expressions

i don't think that the answer in the book is right for this one

$\frac{15a^2b}{4c} \div \frac{8abc}{-3}$

i know that you have to times it by the reciprocal
the non-reduced answer that i got is:

$-\frac{45a^2b}{60a^2bc}$

the only way that i can think to reduce this is by dividing the top and bottom by 5 but that leaves 9 on the top and 12 on the bottom which can be reduced further.
also
the answer in the back of the book is

$-\frac{45a}{32c^2}$
how do you get it if it is.

2. Originally Posted by t-dot
i don't think that the answer in the book is right for this one

$\frac{15a^2b}{4c} \div \frac{8abc}{-3}$

i know that you have to times it by the reciprocal
the non-reduced answer that i got is:

$-\frac{45a^2b}{60a^2bc}$

the only way that i can think to reduce this is by dividing the top and bottom by 5 but that leaves 9 on the top and 12 on the bottom which can be reduced further.
also
the answer in the back of the book is

$-\frac{45a}{32c^2}$
$\frac{15a^2b}{4c} \div \frac{8abc}{-3}= \frac{15a^2b}{4c} \cdot \frac{-3}{8abc}$
As you easily can see you calculated $4 \cdot 8 = 60$ which isn't correct too often