若x(y-1)-y(x-1)=4,则x2+y2/2-xy=_____________请尽快,

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若x(y-1)-y(x-1)=4,则x2+y2/2-xy=_____________请尽快,若x(y-1)-y(x-1)=4,则x2+y2/2-xy=_____________请尽快,若x(y-1)-

若x(y-1)-y(x-1)=4,则x2+y2/2-xy=_____________请尽快,
若x(y-1)-y(x-1)=4,则x2+y2/2-xy=_____________
请尽快,

若x(y-1)-y(x-1)=4,则x2+y2/2-xy=_____________请尽快,
x(y-1)-y(x-1)=4
xy-x-xy+y=4
-x+y=4
x-y=-4
(x²+y²)/2-xy
=(x²-2xy+y²)/2
=(x-y)²/2
=(-4)²/2
=8

x(y-1)-y(x-1)=4
xy-x-yx+y=4
y-x=4
...
y2/2什么哦

等于8