(x²-x)²-8x²+8x+12=(x²-x)²-8(x²-x)+12=(x²-x-2)(x²-x-6)=(x-2)(x+1)(x-3)(x+2)
(x^2-x)^2-8x^2+8x+12=x^2(x-1)^2-8x(x-1)+12=[x(x-1)-2][x(x-1)-6]=(x^2-x-2)(x^2-x-6)=(x-2)(x+1)(x-3)(x+2)
