Solve the nonlinear optimization problem
min f (x1,x2) = (x1)^2 −x1x^2 +(x2)^2 −2x2
s.t. g(x1,x2) = x1 +x2 −1 ≤0.
(a) Apply the optimality conditions;
(b) Verify your solution in Excel. Show all steps.