若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于
问题描述:
若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于
答
(x+2y)/(6x-7y)等于0
答
若(x-y)/(x+y)=3
那么x-y=3(x+y)
x-y=3x+3y
故x=-2y
所以(x+2y)/(6x-7y)=(-2y+2y)/(6*(-2y)-7y)=0
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