Find the maximum and minimum values of the function f(x,y)=4𝑥^2 +9𝑦^2
they occur where the partials are zero, right?
plus, don't forget what you already know -- this is just an elliptical parabaloid with vertex at (0,0)
plus, don't forget what you already know -- this is just an elliptical parabaloid with vertex at (0,0)