x³－x² +12 =x³+8-(x²-4)=(x+2)(x²-2x+4)-(x+2)(x-2)=(x+2)(x²-3x+6)x³+x²-10x-6 =x³-27+x²-10x+21=(x-3)(x²+3x+9)+(x-7)(x-3)=(x-3)(x²4x+2)