已知1/x-1/y=5 求分式-x+xy+y/2x+7xy-2y

stornman 1年前 已收到2个回答 举报

zl_chill 幼苗

共回答了13个问题采纳率:92.3% 举报

将1/x-1/y=5通分,得y-x/xy=5,
两边同时乘以xy,得y-x=5xy,
带入-x+xy+y/2x+7xy-2y,得5xy+xy/-2*5xy+7xy,
合并同类项,得6xy/-3xy=-2
即,原式等于-2

1年前

5

lfboc 幼苗

共回答了2个问题 举报

1/x-1/y=5
所以y-x=5xy
y+xy-x/2x+7xy-2y
=y-x+xy/7xy-2(y-x)
=5xy+xy/7xy-2*5xy
=6xy/-3xy=-2

1年前

0
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