已知XY=8,满足Xˇ2Yˇ-XYˇ2-X+Y=56,求Xˇ2+Yˇ2的值

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已知XY=8,满足Xˇ2Yˇ-XYˇ2-X+Y=56,求Xˇ2+Yˇ2的值
已知XY=8,满足Xˇ2Yˇ-XYˇ2-X+Y=56,求Xˇ2+Yˇ2的值

已知XY=8,满足Xˇ2Yˇ-XYˇ2-X+Y=56,求Xˇ2+Yˇ2的值
在线数学帮助你:
这是一道关于化简求解的题目;
根据题目给出的式子:
X^2Y-XY^2-X+Y=56;
提出XY;XY(X-Y)-(X-Y)=56;
再提出(X-Y)可得;(XY-1)(X-Y)=56;
因为XY=8;XY-1=7;那么就有:
7(X+Y)=56;X-Y=8;
运用一下完全平方公式:(X-Y)^2=X^2-2XY+Y^2=8^2=64;
因此;X^2+Y^2=64-2XY=64+2*8=80

已知xy=8,满足x²y-xy²-x+y=56,求x²+y²的值
x²y-xy²-x+y=xy(x-y)-(x-y)=(x-y)(xy-1)=(x-y)(8-1)=7(x-y)=56,故x-y=8
(x-y)²=x²-2xy+y²=x²+y²-16=64,∴x²+y²=80

Xˇ2Yˇ-XYˇ2-X+Y=56
xy(x-y)-(x-y)=56
(x-y)(xy-1)=56
7(x-y)=56
x-y=8
两边平方得:
x²+y²-2xy=64
x²+y²=64+2xy=64+16=80