# How do you factor #45r^2-120rs+80s^2#?

##### 1 Answer

Mar 30, 2016

#### Explanation:

First separate out the common scalar factor

#45r^2-120rs+80s^2=5(9r^2-24rs+16s^2)#

Next note that both

#(3r-4s)^2 = (3r)^2-2(3r)(4s)+(4s)^2 = 9r^2-24rs+16s^2#

So