(x+1)²(x+2)-(x+1)(x+2)²
=(x+1)(x+2)[x+1-x-2)
=-(x+1)(x+2)
9x^5-35x³-4x
=x(9x^4-35x^2-4)
=x(9x^2+1)(x^2-4)
=x(9x^2+1)(x+2)(x-2)
(x+1)²(x+2)-(x+1)(x+2)²
=(x+1)(x+2)[x+1-x-2)
=-(x+1)(x+2)
9x^5-35x³-4x
=x(9x^4-35x^2-4)
=x(9x^2+1)(x^2-4)
=x(9x^2+1)(x+2)(x-2)