Final answer:
The rate of change of f(x,y)=3xy+y^2 at the point (3,1) in the direction v=-3i-3j can be found by calculating the dot product of the gradient of f and the normalized direction vector v. The direction of maximum rate of change of f at (3,1) is in the direction of the gradient vector ∇f. The maximum rate of change is equal to the magnitude of the gradient of f at (3,1).
Step-by-step explanation:
(a) To find the rate of change of the function f(x,y)=3xy+y^2 at the point (3,1) in the direction v = -3i - 3j, we calculate the dot product of the gradient of f at (3,1) and the normalized direction vector v.
(b) The direction of maximum rate of change of f at (3,1) is in the direction of the gradient vector ∇f.
(c) The maximum rate of change is equal to the magnitude of the gradient of f at (3,1).