계산 lim(n→∞)∑상하 k=1(k+2)/[k!+(K+1)!+(K+2)!]

계산 lim(n→∞)∑상하 k=1(k+2)/[k!+(K+1)!+(K+2)!]

원형=∑(k+2)/[k!(1+k+1+(k+1)(k+2)]=∑1/(k!(k+2))
령 S(x)=∑1/k!(k+2)*x^(k+2),분명히 S(0)=0
S'(x)=∑1/k!x^(k+1)=x∑1/k!*x^k
=x(e^x-1)
S(X)=∫x(e^x-1)dx=∫xe^xdx-∫xdx
=xe^x-e^x-x^2/2+c
S(0)=-1+C=0
∴C=1
S(X)=xe^x-e^x-x^2/2+1
받다
원 급수=e-e-1/2+1=1/2