Determine whether each of the following relations are reflexive, symmetric, and transitive.
Show that the relation R in the set R of real numbers, defined as
R = {(a, b): a ≤ b2 } is neither reflexive nor symmetric nor transitive.
Check whether the relation R defined in the set {1, 2, 3, 4, 5, 6} as
R = {(a, b): b = a + 1} is reflexive, symmetric or transitive.
Minimise \( z = 5x - 2y \)
Subject to the constraints:\[ x + 2y \leq 120, \\ x + y \geq 60, \\ x - 2y \geq 0, \\ x \geq 0, \\ y \geq 0. \]