Exam-style question
Try this first
Let X = {a, b} and Y = {1, 2, 3}. Which set is X × Y?.
- A.{(a, 1), (a, 2), (a, 3), (b, 1), (b, 2), (b, 3)}
- B.{(1, a), (2, a), (3, a), (1, b), (2, b), (3, b)}
- C.{a, b, 1, 2, 3}
- D.{(a, b), (1, 2, 3)}
Model answer
What a good answer should say
- {(a, 1), (a, 2), (a, 3), (b, 1), (b, 2), (b, 3)}
Explanation
Why this works
X × Y contains every ordered pair (a, b) in which the first value is from X and the second value is from Y. There are 2 × 3 = 6 ordered pairs.
Common mistake
No common mistake is linked to this question yet.