1. The problem statement, all variables and given/known data 1. for the surface z=9 - x^2 - y^2 find, i) the gradient at (1,1,7) in the direction making an angle alpha with the x axis ii) the max gradient at the point (1,1,7) and the value of alpha for which it occurs 2. find the stationary point of z=x^2 +2x +3y^2 -3xy + 5 and determine the nature of this point 2. Relevant equations this is what i need, im not sure of the equation you use to differentiate an equation like this. 3. The attempt at a solution I know you have to partially diff it with respect to x and then with respect to y, but I don't know how to combine the 2 together so you can just put the numbers in and find the gradient.