Show that the function (x, y) = xy 2 in Exercise 7, subject to x + 2y

Show that the function ƒ(x, y) = xy² in Exercise 7, subject to x + 2y = 15, does not have an absolute minimum or maximum.

Exercise 7

Find the relative maxima or minima in Exercises.

Maximum of ƒ(x, y) = xy², subject to x + 2y = 15