若3x+2y=0,求(1- x/x+y + 2y^2/x^2-y^2)÷(1 + 2y/x-y)

若3x+2y=0,求(1- x/x+y + 2y^2/x^2-y^2)÷(1 + 2y/x-y)

题目
若3x+2y=0,求(1- x/x+y + 2y^2/x^2-y^2)÷(1 + 2y/x-y)
答案
原式=[(x+y)/(x+y)-x/(x+y)+2y²/(x+y)(x-y)]÷(x-y+2y)/(x-y)
=[y/(x+y)+2y²/(x+y)(x-y)]×(x-y)/(x+y)
=(xy-y²+2y²)/(x+y)(x-y)×(x-y)/(x+y)
=y(x+y)/(x+y)×1/(x+y)
=y/(x+y)
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