Question

A relation R is defined from {2, 3, 4, 5} to {3, 6, 7, 10} by : $xRy\iff x$ is relatively prime to y. Then, domain of R is

• A. {2, 3, 5}
• B. {3, 5}
• C. {2, 3, 4}
• D. {2, 3, 4, 5}

Answer 1

The correct option is D

{2, 3, 4, 5}

From {2, 3, 4, 5} to {3, 6, 7, 10}, $xRy\iff x$ is relatively prime to y

2 is relatively prime to 3, 7

3 is relatively prime to 7, 10

4 is relatively prime to 3, 7

5 is relatively prime to 3, 6, 7

So, domain of R is {2, 3, 4, 5}