x的平方y-4y+3xy+xy的平方-y的平方=y(x^2+3x-4)+y^2(x-1)=y(x+4)(x-1)+y^2(x-1)=y(x-1)(x+4+y)x的平方y-4xy+4y-y的3次方=y(x^2-4x+4-y^2)=y[(x-2)^2-y^2]=y(x-2+y)(x-2-y)你能明白,赞同