4x²+2x-9y²+3y,x²+6y-y²-9,x²-xy-2y²-x-y,x²-y²-x-y
问题描述：
4x²+2x-9y²+3y,x²+6y-y²-9,x²-xy-2y²-x-y,x²-y²-x-y
2m(a-c)-5(c-a) ,3a(x-y)²-2(y-x)²
答
4x²+2x-9y²+3y=(4x²-9y²)+(2x+3y)=(2x+3y)(2x-3y)+(2x+3y)=(2x+3y)(2x-3y+1)x²+6y-y²-9=x²-(y-3)²=(x+y-3)(x-y+3)x²-xy-2y²-x-y,=(x+y)(x-2y)-(x+y)=(x+y)(x-2y-...