x(x-1)-(x²+y)=3 求2分之x²+y²+xy的值

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x(x-1)-(x²+y)=3求2分之x²+y²+xy的值x(x-1)-(x²+y)=3求2分之x²+y²+xy的值x(x-1)-(x

x(x-1)-(x²+y)=3 求2分之x²+y²+xy的值
x(x-1)-(x²+y)=3 求2分之x²+y²+xy的值

x(x-1)-(x²+y)=3 求2分之x²+y²+xy的值
∵x(x-1)-(x²+y)=3
∴x²-x-x²-y=3
∴x+y=-3
∴(x²+y²)/2+xy
=(x²+y²+2xy)/2
=(x+y)²/2
=9/2