Question

factor the polynomial x^3+4x^2+16x+64

Answer 1

$$x^3+4x^2+16x+64=x^2(x+4)+16(x+4)=(x+4)(x^2+16)= $$
$$=(x+4)(x+2i)(x-2i) $$

Answer 2

Oooooo! There is a mistake=(

Answer 3

The last line
$$ =(x+4)(x+4i)(x-4i)$$