Question

A relation R is defined from {2, 3, 4, 5} to {3, 6, 7, 10} by :$(x,y)\in R\to x$ 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}

Given set $A=\{2,3,4,5\}$ to $B=\{3,6,7,10\}$

is defined as $(x,y)\in R\Rightarrow x$ is relatively prime to $y$

So $(2,3)\in R$

Similarly, $2$ is relatively prime to $7$ so that $(2,7)\in R$

So, we get $R=\{(2,3),(2,7),(3,7),(3,10),(4,3),(4,7),(5,3),(5,6),(5,7),\}$

Thus domain $\{2,3,4,5\}$