1. The problem statement, all variables and given/known data max f(x, y) = 2xy + 2y − x^2 − 2y^2 I need to get the value of x and y and determine if it gives the global maximum by using the infinity approach only. Boundary is Negative infinity and Positive infinity 2. Relevant equations max f(x, y) = 2xy + 2y − x^2 − 2y^2 3. The attempt at a solution I am aware of the first step: Partial differentiate with respect to x ++++++ 2y − 2x = 0 Partial differentiate with respect to y ++++++ 2x+ 2− 4y = 0 Solving both the equations will give x = y = 1 From here, I do not know how to use f(±INFINITY,±INFINITY) to determine if x = y = 1 yields the global maximum. Your help is greatly appreciated. I have an exam next week on this. Thanks Rye.