Representar por enumeração os conjuntos:
a = { x | x é divisor de 12 }
b = { x | x maior igual a 2 e x é par }

faça axb e bxa

A={1,2,3,4,6,12}

B={2,4,6,8,10,12...}

AXB={(1,2), (1,4), (1,6)(1,8)(1,10), (1,12), ( (2,2), (2,4), (2,6)(2,8)(2,10), (2,12),(1,2), (3,4), (3,6)(3,8)(3,10), (3,12),(4,2), (4,4), (4,6)(4,8)(4,10), (4,12),(6,2), (6,4), (6,6)(6,8)(6,10), (6,12),(12,2), (12,4), (12,6)(12,8)(12,10), (12,12)}

BXA={(2,1)(2,2)(2,3)(2,4), (2,6), (2,12), (4,1)(4,2)(4,3)(4,4), (4,6), (4,12), (6,1)(6,2)(6,3)(6,4), (6,6), (6,12), (10,1)(10,2)(10,3)(10,4), (10,6), (10,12), (12,1)(12,2)(12,3)(12,4), (12,6), (12,12)

Explicação passo-a-passo:

Temos que:

B = {-4, -3, -2, -1, 1, 2, 3, 4}

-> Z*: números inteiros não-nulos