#derivative, || Find the derivative of log x by using first principle of derivative.

In the following link i have explained the derivative of x^2 by using first principle of derivative.
In the following link i have explained the derivative of sin x by using first principle of derivative:
In the following link i have explained the derivative of e^{x} by using first principle of derivative:
If f(x)=xe^{x}$, then find f''(x). Also find the n-th derivative $f^{n}\left(x\right)$