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已知2x=-y,求分式x^2-y^2分之xy的值
人气:398 ℃ 时间:2019-10-17 03:30:09
解答
2x=-y
y=-2x
xy/(x^2-y^2)
=x*(-2x)/[x^2-(-2x)^2]
=-2x^2/[x^2+4x^2]
=-2x^2/5x^2
=-2/5
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