i could get the directional derivative which is -12. but how to get the unit vector out of it?Consider the function .
Find the the directional derivative of at the point in the direction given by the angle . Find the unit vector which describes the direction in which is increasing most rapidly at .
The given function is . I have already told you that evaluated at the given point is the direction of maximum rate of change. And I have also told you to divide that vector by it's magnitude to get a unit vector in that direction.
I cannot see that you have done or attempted to do any of what I said.
By the way, "-12" is a scalar not a vector.