在微积分学中,指数函数f(x)=e~(-x)~(-2)(x≠0)是一个非常简单而十分重要的初等偶函数,尤其是在函数的幂级数展开中,需要研究这个指数函数的有限形式的高阶导数及其性质.本文对此问题进行了研究,并得到如下结果:设f(x)=e~(-x)~(-2)(x≠0)的n阶导数为f_n(x)=fn(x)e~(-x)~(-2),则f_n(x)=sum from i=1 to n(-1)~(n+i)C_i(n)x~(-n-2i),其中C_1(n)=(n+1)!,C_i(n)=2sum from j=i to n(n+2i-1)!/(j+2i-1)!C_(i-1)(j-1),(1〈i≤n).
Abstract: This paper studies the higher order derivatives of the exponential functionf(x)=e~(-x)~(-2)(x≠0)obtains the following result: Suppose that the nth order derivative of the functionf(x)=-x-2(x≠0)is(f(n)(x)=fn(x)e-x-2,then fn(x)+n∑i=1(-1)n+iCi(n)x-n-2i,WhereC1(n)=(n+1)!,Ci(n)=2n∑j=i(n+2i-1)!/(j+2i-1)!Cii(j-1),(1〈i≤n).