已知(1/x)-(1/y)=5,求(2x+5xy-2y)/(x-2xy-y)

问题描述:

已知(1/x)-(1/y)=5,求(2x+5xy-2y)/(x-2xy-y)

(1/x)-(1/y)=5
(2x+5xy-2y)/(x-2xy-y) 分子,分母除以xy得
(2/y+5-2/x)/(1/y-2-1/x)
=(2*5+5)/(-5-2)
=-15/7