Questionb. Find the direction derivatives of $\phi=x^{2} y z+4 x z^{2}$ at $(1,-2,-1)$ in the direction $2 i-j-2 k$

Studdy Solution
Thus, the directional derivative of $\phi$ at $(1, -2, -1)$ in the direction $2\mathbf{i} - \mathbf{j} - 2\mathbf{k}$ is:
$$\boxed{\frac{37}{3}}$$