The function f(x,y) = x + y has an absolute maximum value and absolute minimum value subject to the constraint 9x- - 9xy + 9y- =9. Use Lagrange multipliers to find these values. The absolute maximum value is . (Type an exact answer.)The function f(x,y) =7xy has an absolute maximum value and absolute minimum value subject to the constraint x~ + y- - xy =9. Use Lagrange multipliers to find these values. Find the gradient of f(x,y) = 7xy. Vf(x,y) =The function f(x,y) =e" has an absolute maximum value and absolute minimum value subject to the constraint x + xy + y- =9. Use Lagrange multipliers to find these values. The absolute maximum is (Type an exact answer in terms of e.)