(x^2 +4x +4) (x^2 -2x -1) - (x^2 +16) (x^2 +8x +16)
-x^2 -16 (x^2 +8x +16)
-x^4 -8x^3 -16x^2 -16x^2 -128x -256
x^4 -2x^3 -x^2 + 4x^3 -8x -4x +4x^2 -8x -4 -x^2 - 16 -x^4 -8x^3 -16x^2 -16x^2 -128x -256
It's not finished yet I know. Once I started collecting like terms, I notice something was done wrong.