Find the Directional Derivative to the Given Function at the Specified

Essay

Find the directional derivative to the given function at the specified point $P$ in the direction of the vector $\vec { u }$ $f ( x , y , z ) = x y z ^ { 2 } , P = ( 1,2,1 ) , \vec { u } = \left\langle \frac { 1 } { 2 } , 0 , \frac { \sqrt { 3 } } { 2 } \right\rangle$