x2+4y2=2(x-2y)-2,求x,y的值
问题描述：
x2+4y2=2(x-2y)-2,求x,y的值
答
x^2+4y^2=2(x-2y)-2
x^2+4y^2=2x-4y-2
x^2+4y^2-2x+4y+2=0
(x^2-2x+1)+4(y^2+y+1/4)=0
(x-1)^2+4(y+1/2)^2=0
要使式子成立,则x-1=0 y+1/2=0
所以x=1 y=-1/2