First find the gradient by using partial derivatives.
Sub in given point (0,-1,2) for x,y,z
∨
Next, find unit vector from directional vector (0,-1,2) --> (-3,4,-3)
Finally, use dot product on gradient and unit vector to get directional rate of change.
Answer is approx 61.398
Sub in given point (0,-1,2) for x,y,z
∨
Next, find unit vector from directional vector (0,-1,2) --> (-3,4,-3)
Finally, use dot product on gradient and unit vector to get directional rate of change.
Answer is approx 61.398