How do you factor #x^3+2x^2-8x-16#?
1 Answer
Aug 28, 2016
Explanation:
Given:
#x^3+2x^2-8x-16#
Notice that the ratio between the first and second terms is the same as that between the third and fourth terms.
So this cubic will factor by grouping:
#x^3+2x^2-8x-16#
#=(x^3+2x^2)-(8x+16)#
#=x^2(x+2)-8(x+2)#
#=(x^2-8)(x+2)#
#=(x^2-(2sqrt(2))^2)(x+2)#
#=(x-2sqrt(2))(x+2sqrt(2))(x+2)#
