计算题……帮忙算算~……………………急用计算:1.(a^2-4)/(a^2+4a+4)*2a/(a^2-4a+4)2.(x^2y-x^3/x^2+2xy+y^2)/(x/x-y)*(x+y/x^2-2xy+y^2)3.(x/(x-y)-x^2/(x^2-2xy+y^2))/(x/(x+y)-x^2/(x^2-y^2))4.（x^2-x-2/(x^2-4x+4)-x/x^2-2x）*(x-4/x)
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1.2a/(a^2-4)
======以下答案可供参考======
供参考答案1:
分太低了...