已知x(x-1)-(x的2次方-y)=3,求x的2次方+y的2次方/2-xy

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已知x(x-1)-(x的2次方-y)=3,求x的2次方+y的2次方/2-xy
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已知x(x-1)-(x的2次方-y)=3,求x的2次方+y的2次方/2-xy
已知x(x-1)-(x的2次方-y)=3,求x的2次方+y的2次方/2-xy

已知x(x-1)-(x的2次方-y)=3,求x的2次方+y的2次方/2-xy
x²-x-x²+y=3
-x+y=3
x-y=-3
所以原式=(x²-2xy+y²)/2
=(x-y)²/2
=9/2


x(x-1)-(x²-y)=3
x²-x-x²+y=3
y-x=3
(x²+y²)/2-xy
=(x²-2xy+y²)/2
=(y-x)²/2
=3²/2
=9/2