Question

A relation R is defined from [2, 3, 4, 5] to [3, 6, 7, 10] by : x R y ⇔ 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

(d) {2, 3, 4, 5}

Given:
From {2, 3, 4, 5} to {3, 6, 7, 10}, x R y ⇔ 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}