Find the critical points and classify them as local maxima, local minima, saddle points, or none of these. (Order your answers by their ordered pairs, from smallest to largest x, then from smallest to largest y.)

f(x, y) = 8xy − (1/4)(x + y)^4

The john deere company has found that revenue,in dollars, from sales of heavy-duty tractors is a function of the unit price p, in dollars, that it charges. if therevenue r is r(p)= -1/2p^2 +1900pa)how much revenue will the company generate if they sell 700 tractors? b) how many tractors does the company want to sell to maximize the revenue?