If A = {1, 2, 3, 4, 5} and B = {1, 2, 3}, how many ordered pairs (x, y) in A × B satisfy x = 2y - 1?
Answer and explanation
Correct answer: 3
Use each possible y from B and calculate x = 2y - 1. For y = 1, x = 1, giving (1,1); for y = 2, x = 3, giving (3,2); and for y = 3, x = 5, giving (5,3). All three calculated x-values belong to A, and every y-value belongs to B. Therefore, the valid ordered pairs are (1,1), (3,2), and (5,3), so their number is 3 and option C is correct.
Frequently asked questions
What is the correct answer to this question?
3
Why is this the correct answer?
Use each possible y from B and calculate x = 2y - 1. For y = 1, x = 1, giving (1,1); for y = 2, x = 3, giving (3,2); and for y = 3, x = 5, giving (5,3). All three calculated x-values belong to A, and every y-value belongs to B. Therefore, the valid ordered pairs are (1,1), (3,2), and (5,3), so their number is 3 and option C is correct.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Sets. Topic: The Empty Set, Finite and Infinite Sets, Equal Sets.
