(x/x+y +2y/x+y)乘以xy/ x+2y除以(1/x+1/y)（2）（3x^2/4y)^2乘以2y/3x+ x^2/2y^2除以2y^2/x

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(x/x+y +2y/x+y)乘袭芹以xy/ x+2y除以弯禅悔(1/x+1/y)

=(x+2y)/(x+y)*xy/埋正(x+2y)/[(x+y)/(xy)]

=xy/(x+y)*xy/(x+y)

=(xy)^2/(x+y)^2

（3x^2/4y)^2乘以2y/3x+ x^2/2y^2除以2y^2/x

=9x^4/16y^2*2y/3x+x^2/2y^2*x/2y^2

=3x^3/8y+x^3/4y^4

=(3x^3y^3+2x^3)/8y^4

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