Hello Amit,

The solution to your question, using the exponential integral function, is Ei(e to the power x)+C.

If you do a substitution where u=e to the power x and thus du=e to the power x dx, your integrand becomes

e to the power u /u du, so the definition of the exponential integral can be applied and the integral becomes Ei(u)+C=Ei(e to the power x)+C.

Hope this helps.