x二次方+2x-y的二次方+8y-15
问题描述：
x二次方+2x-y的二次方+8y-15
题没一个括号
答
x^2+2x-y^2+8y-15
=(x^2+2x+1)-(y^2-8y+16)
=(x+1)^2-(y-4)^2
=(x+y-3)(x-y+5)