已知x、y满足x^2+y^2=2x+y-5/4,求x^2-2xy-y^2的值

问题描述:

已知x、y满足x^2+y^2=2x+y-5/4,求x^2-2xy-y^2的值
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配方得,(x-1)^2+(y-1/2)^2=0,所以x=1,y=1/2,所以x^2-2xy-y^2=-1/4