=-(x的4次方-x²-12)=-(x²-4)(x²+3)=-(x+2)(x-2)(x²+3)2x的3次方-3x的2次方+3y的2次方-2xy的2次方=x²(2x-3)-y²(2x-3)=(2x-3)(x²-y²)=(2x-3)(x+y)(x-y)