If A = {(x, y) : x, y ∈ {1, 2, 3}, x < y} and B = {(x, y) : x + y = 4}, what is A ∩ B?
Answer and explanation
Correct answer: {(1, 3)}
First list the ordered pairs allowed by x < y: (1,2), (1,3), and (2,3). Now test the second condition x + y = 4. Only (1,3) has sum 4. The pair (3,1) also has sum 4, but it fails x < y, while (2,2) fails the strict inequality. Therefore the intersection contains only {(1,3)}.
Frequently asked questions
What is the correct answer to this question?
{(1, 3)}
Why is this the correct answer?
First list the ordered pairs allowed by x < y: (1,2), (1,3), and (2,3). Now test the second condition x + y = 4. Only (1,3) has sum 4. The pair (3,1) also has sum 4, but it fails x < y, while (2,2) fails the strict inequality. Therefore the intersection contains only {(1,3)}.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Sets. Topic: Operations on Sets (Union, Intersection, Difference).