函数的二阶导数y等于x的平方根份之1-x，求y‘及y”

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y=1/兄芦根号x-根号销御x
y'亏尘岩=(-1/2)*x^(-3/2)-(1/2)*x^(-1/2)
y"=(3/4)*x^(-5/2)+(1/4)*x^(-3/2)

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