(x-y分之2x的平方乘以x+y分之y)-(x的4次方-y的4次方分之x的4次方y除以(x的平方+y的平方分之x的平方)的平方
人气：172 ℃ 时间：2020-03-17 01:47:55
解答
原式=[2x/(x-y)]*[y/(x+y)]-[x^4/(x^4-y^4)]/[x^2/(x^2+y^2)]^2=2xy/(x^2-y^2)-(x^2+y^2)^2/[(x^2+y^2)(x^2-y^2)]=2xy/(x^2-y^2)-(x^2+y^2)/(x^2-y^2)=-(x-y)^2/[(x+y)(x-y)]=(y-x)/(x+y).
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