Gradient. A scalar field is given by f(x,y,z) = e^xy cos(z)

a) Evaluate the gradient of the function given above.

b) At the point P located at (x,y,z) = (0.2, 1.3, -0.25), what is the unit vector pointed in the direction of maximum change for the function f ?

c) What is the derivative of the function at the point (x,y,z) = (1, -2, 0.5) along a line from that point to the point (x,y,z) = (3,4,-5)?