x^2-4xy+3y^2-4x+10y+3
=（x-y)(x-3y)-4x+10y+3
=(x-y-3)(x-3y-1)
x^2+xy-2y^2+2x+7y-3
=(x-y)(x+2y)+2x+7y-3
=(x-y+3)(x+2y-1)（x-y)(x-3y)-4x+10y+3到(x-y-3)(x-3y-1)，(x-y)(x+2y)+2x+7y-3到(x-y+3)(x+2y-1)怎么来的十字相乘法x-y -3 x-y3 ╳ ╳x-3y -1 x+2y-1(x-y-3)(x-3y-1)(x-y+3)(x+2y-1)再详细些，列个式子，我数学比较差十字相乘法x-y -3 x-y3 ╳ ╳x-3y -1x+2y-1(x-y-3)(x-3y-1)(x-y+3)(x+2y-1)这就是列的式子