When you calculate a directional derivative, you need to do the inner product with a unit vector. The unit vector in the direction is . So when you take the dot product, you should get . I assume your answer 5/sqrt(5) is a typo.
- Hollywood
When you calculate a directional derivative, you need to do the inner product with a unit vector. The unit vector in the direction is . So when you take the dot product, you should get . I assume your answer 5/sqrt(5) is a typo.
- Hollywood