求指定点函数的导数f(x)=1/√x x=1,x=4 先求的函数的导数式再求解,

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f(x)=x^(-1/2) f'(x)=(-1/2)*x^(-1/2-1)=(-1/2)*x^(-3/2) x=1时,f'(x)=-1/2 x=4时,f'(x)=(-1/2)*4^(-3/2)=(-1/2)*(1/8)=-1/16