5. Determine the truth value of each expression below ifthe domain is the set of all real numbers. (4 pts) If true, give an example.) (If false, give a counterexample.) (f false, give a counterexample.) d.3xay3x(x2 + y2-Z2) (lftrue, give an example.) 2 6. Redo the above (problem 1), with the domain of positive integers. (4 pts) b. C. d