Question

The relation R define on the set of natural numbers as {(a, b) : a differs from b by 3} is given.

• A. $\left\{\right(1,4),(2,5),(3,6),........\}$
• B. $\left\{\right(4,1),(5,2),(6,3),........\}$
• C. $\left\{\right(1,3),(2,6),(3,9),........\}$
• D. None of above

Answer 1

The correct option is B $\left\{\right(4,1),(5,2),(6,3),........\}$

Let $R=\left\{\right(a,b):a,b\in N,a-b=3\}$
$=\left\{\right(n+3,n):n\in N\}$
$=\left\{\right(4,1),(5,2),(6,3).......\}$

Hence, option B is correct.