题目

计算 [(2/3x)-(2/x+y)(x+y/3x-x-y)]÷(x-y/x) [1/(a+b)²-1/（a-b）²]÷（1/a+b - 1/a-b)
一:[(2/3x)-(2/x+y)(x+y/3x-x-y)]÷(x-y/x)
二:[1/(a+b)²-1/（a-b）²]÷（1/a+b - 1/a-b)

提问时间：2021-01-20

答案

一:[(2/3x)-(2/x+y)(x+y/3x-x-y)]÷(x-y/x) =[(2/3x)-2/(2x-y)]÷(x-y/x) =2/(3(x-y))-2x/(3(2x-y)(x-y)) =(2(2x-y)-2x*3)/(3(2x-y)(x-y)) =(-2(x+y))/(3(2x-y)(x-y)) =(-2x-2y)/(6x^2-9xy+3y^2)二:[1/(a+b)
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