Is x+1 a factor of x^3+8x^2+11x-20?

1 Answer
Nov 8, 2016

(x+1) is not a factor, but (x-1) is.

Explanation:

Given p(x)=x^3+8x^2+11x-20 if x+1 is a factor of p(x) then

p(x)=(x+1)q(x) so for x=-1 we must have

p(-1)=0

Verifying on p(x)

p(-1)=(-1)^3+8(-1)^2+11(-1)-20=-24

so (x+1) is not a factor of p(x)

but (x-1) is a factor because

p(1)=1+8+11-20=0