f(x)=e^-x,则∫f'(lnx)/xdx等于?,
问题描述:
f(x)=e^-x,则∫f'(lnx)/xdx等于?,
答
f '(x)=-e^(-x)
所以f '(lnx)=-e^(-lnx)=-1/[e^(lnx)]=-1/x
故∫f'(lnx)/xdx
=∫-1/x²dx
=1/x +C