How do you factor #-5a ^ { 7} + 20a ^ { 6} - 20a ^ { 5}#?

1 Answer
May 15, 2017

Answer:

#-5a^5(a-2)^2#

Explanation:

When factorising, first look for common factors.

#-5a^7+20a^6-20a^5#

Here we have #-5a^5# as the GCF

#-5a^5(a^2-4a+4)#

then look to see if the bracket can be factorised separately

we note it is a quadratic, and a perfect square at that

#-5a^5(a-2)^2#