已知实数x、y满足x^2+y^2-xy+2x-y+1=o,试求x、y的值
问题描述：
已知实数x、y满足x^2+y^2-xy+2x-y+1=o,试求x、y的值
答
x^2+y^2-xy+2x-y+1=0
x^2+2x+1-y(x+1)+y^2=0
(x+1)^2-y(x+1)+y^2=0
(x+1-y/2)^2+3y^2/4=0
所以y=0,x+1-y/2=0,
得x=-1
最后为x=-1,y=0