（x-2y）(2x+3y)-2(2y-x)(5x-y)
=(x-2y)[(2x+3y)+2(5x-y)]
=(x-2y)[2x+3y+10x-2y]
=(x-2y)(12x+y)3x^2(x-y)+6x(y-x)用提公因式法将下列各式分解因式怎么算3x^2(x-y)+6x(y-x)=3x(x-y)(x-2)