已知x/y=3,求x²+y²-xy/x²-y²的值.
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已知x/y=3,求x²+y²-xy/x²-y²的值.
已知x/y=3,求x²+y²-xy/x²-y²的值.
已知x/y=3,求x²+y²-xy/x²-y²的值.
x/y=3
则x=3y
所以x²=9y²
xy=3y²
所以原式=(9y²+y²-3y²)/(9y²-y²)
=7y²/8y²
=7/8
x/y=3, 知道 X=3Y 把X=3Y
带入
x²+y²-xy/x²-y²=9y²+y²-3y²/9y²-y²=7/8