In this problem, the domain of discourse is the set of positive integers: {1, 2, 3,...}. Which statements are true? If an existential statement is true, give an example.

If a universal statement is false, give a counterexample.

(a)x(x21>0)

(b)x(x2x >0)

(c)x(x3= 8)

(d)x(x+ 1 = 0)