已知xy满足等式x^2+2x+x^2y^2+2xy+2=0那么x+y的值是
问题描述:
已知xy满足等式x^2+2x+x^2y^2+2xy+2=0那么x+y的值是
答
(x+1)^2+(xy+1)^2=0
xy=-1
x=-1
y=1
x+y=0