分解因式x^2+2xy+y^2+2x+2y-3
问题描述：
分解因式x^2+2xy+y^2+2x+2y-3
答
x^2+2xy+y^2+2x+2y-3
=(x+y)²+2(x+y)+3
=(x+y+3)(x+y-1)