Problem

(J) Find the directional derivative of $f(x,y,z)=x^y z^2$ at the point $(e,e,1)$ in the direction $\mathbf{u}=\dfrac{3}{13}\mathbf{i}+\dfrac{12}{13}\mathbf{j}+\dfrac{4}{13}\mathbf{k}$. Answer: $\underline{\quad(11)\quad}$.