How do you factor #-9a^2-9a#?

1 Answer
Nov 24, 2015

Answer:

#-9a(a+1)#

Explanation:

What is a common factor of the equation?
First lets look at #9#

The two numbers #-9# and #-9# both have a common factor of #-9#, so we can take out a #-9# by dividing the equation by #-9# and placing it on the outside of the brackets.

Factoring out -9

#-9((cancel(-9)a^2)/cancel(-9)+(cancel(-9)a)/cancel(-9))#

New equation: #-9(a^2+a)#

Now lets look at #a#

The common factor of #a^2# and #a# is #a#. Take out #a# by dividing the inside of the brackets by #a# and placing it on the outside

Factoring out the a
#-9a((a^cancel2)/cancela+cancela/cancela)#
New equation: #-9a(a+1)#

Note: Keep in mind that #a/a# is #1#, not zero, because #1/1# is not zero either, so we have to keep a #1# after cancelling out #a/a#.