若xy分之x+y=x-y分之1 求xy分之x²+y²的值.

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若xy分之x+y=x-y分之1求xy分之x²+y²的值.若xy分之x+y=x-y分之1求xy分之x²+y²的值.若xy分之x+y=x-y分之1求xy分之x

若xy分之x+y=x-y分之1 求xy分之x²+y²的值.
若xy分之x+y=x-y分之1 求xy分之x²+y²的值.

若xy分之x+y=x-y分之1 求xy分之x²+y²的值.
(x+y)/(xy)=1/(x-y)
(x²-y²)/(xy)=1
两边平方:
(x^4-2x²y²+y^4)/(x²y²)=1
(x^4+2x²y²+y^4)/(x²y²)=5
[(x²+y²)/(xy)]²=5
∴(x²+y²)/(xy)=±√5

左边分子乘右边分母:(x+y(x-y)=XY
x^+y^-2XY=xy
X^-Y^=3XY
所以(X^-y^)/XY=3

(x²+y²)/xy=(x+y)²/xy-2=[(x+y)/xy]² *xy-2=xy/(x-y)-2=x+y-2

x+y/xy=1/x-y
x²-y²/xy=1
x的4次+y的四次-2x²y²/x²y²=1
x的4次+y的四次+2x²y²-4x²y²/x²y²=1
(x²+y²)²/x²y²=5
x²+y²/xy=+-根号5