may any one give the answer with steps please

Question

given the function f(x,y)=3x2-2xy+4y2
in which direction does the function drop most rapidly at the point p (1,1) and calculate the derivative of the function in that direction

Answer 1

So surface z = f(x,y) = 3x^2-2xy+y^2.  The direction of greatest increase is given by the gradient, that is   del f

 del f = partial deriv. with respect to x * ihat vector + partial deriv of f with respect to y *jhat vector.

 

Plug in (1,1) into -del f