已知5x-4y0且xy≠0,求x·x+y·y/x·x-y·y-x+y/x-y得值

发布时间：2020-07-27 21:07:17

解答题

网友回答

=(x2+y2)/(x2-y2)-(x+y)2/(x2-y2)
=(x2+y2-x2-y2-2xy)/(x2-y2)
=-2xy/(x2-y2)
=-2x/y/(x2/y2-1)
=-2×(4/5)/(16/25-1)
=-8/5÷(-9/25)
=40/9
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