Show that the minimum of Z occurs at more than two points. Maximise $z = – x + 2y$, subject to the constraints: $x \geq 3, x + y \geq 5, x + 2y \geq 6, y \geq 0.$

Question

x ≥ 3, x + y ≥ 5, x + 2y ≥ 6, y ≥ 0.