I can't get the right answer to this problem...what am I doing wrong?

(2x-4)(x+1)^2
(2x-4)(x^2+2x+2)
2x^3+4x^2+4x-4x^2-8x-8
2x^3-4x-8 but the answer I'm supposed to get is 2x^3-6x-4
what am I doing wrong? Please help! thanks

(x + 1)^2 = x^2 + 2x + 1

You added to get the last term rather than multiplying.