Question

1. Find the directional derivative of f(x)= x^2=2y in the direction of 3i=4j. Evaluate the directional derivative at the point (1,2,6)

Answer 1

Your f(x) is strange. It should be f(x,y). Do you mean f(x,y) = x^2-2y? If so, then you can take the gradient of f(x,y), then take the dot product of the components with the direction. Then you can plug in the point and solve.

Answer 2

it could be, i'm just taking the problem off of my worksheet and that's what it says.

Answer 3

You might have to use the limit definition of a directional derivative then. The function f(x) might be (x^2)/2.