x), (3, y)} 2. {(x, 1), (x, 2), (x, 3), (y, 1), (y, 2), (y, 3)} 3. {(1, x, 〇), (1, x, □), (1, y, 〇), (1, y, □), (2, x, 〇), (2, x, □), (2, y, 〇), (2, y, □), (3, x, 〇), (3, x, □), (3, y, 〇), (3, y, □)} 4. {(1, 1), (1, 2), (1, 3), (2, 1), (2, 2), (2, 3), (3, 1), (3, 2), (3, 3)} 5. {} ※任意の集合Aに対してA ✖ ∅ = ∅ ✖ A = ∅ 27 演習:直積 答え