I need to find and classify stationary points of:
z = x^2 + 4xy + 4y - 9x + 1
so far I got:
dz/dx = 2x + 4y - 9 and dz/dy = 4x + 4
not sure as to how to go on as Im rubbish at these lol
dz/dx = 2x + 4y - 9=0
dz/dy = 4x + 4=0.
The second of these tells you that for any critical point x=-1, so using the first you find 4y-11=0 or y=11/4.
So now you have the critical point, now you need to determine what type it is.