已知x(x-1)-(x方-y)=-2,求2分之x方+y方再减xy的值

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已知x(x-1)-(x方-y)=-2,求2分之x方+y方再减xy的值
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已知x(x-1)-(x方-y)=-2,求2分之x方+y方再减xy的值
已知x(x-1)-(x方-y)=-2,求2分之x方+y方再减xy的值

已知x(x-1)-(x方-y)=-2,求2分之x方+y方再减xy的值
x(x-1)-(x^2-y)=-2
-- -x+y=-2
-- x-y=2
(x^2+y^2)/2 -xy
=(x^2-2xy + y^2)/2
=(x-y)^2/2
=2

x(x-1)-(x²-y)=-2 x²-x-x²+y=-2 x-y=2 (x²+y²)/2-xy=(x²-2xy+y²)/2=(x-y)²/2=2²/2=2