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

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Answer 1 · 2016-11-08T13:02:29

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

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#