xy Find all second order derivatives for r(x,y) = Find the extremum of f(x,y) subject to the given constraint, and state whether it is a maximum or a minimum. 7x + 2y f ( x, y) = 3x2 + y2 - 2xy; x+ y=9 Find the Lagrange function F(x,y,2). F (x,y,X) = [->(D xx (X,y) = Find the partial derivatives Fx, Fy, and F,. Fx =0 "yy (X,y) = Fy = Fx = "xy (X,y) = [yx (X,y) = There is a value of located at (x, y) =]. (Type an integer or a fraction. Type an ordered pair, using integers or fractions.)