X^3+8x^2+16x-2x^2-16x-32=7x+28
x^3+6x^2-32=7x+28
x^3+6x^2-32-7x-28=0
x^3+6x^2-60-7x=0
x^3+6x^2-7x-60=0
x^3-3x^2+9x^2-27x+20x-60=0
x^2(x-3)+9x(x-3)+20(x-3)=0
(x-3)(x^2+9x+20)=0
(x-3)(x^2+5x+4x+20)=0
(x-3)(x(x+5)+4(x+5))=0
(x-3)(x+5)(x+4)=0
x=3. x=-5 x=-4