Question

Let A = {x : x is a multiple of 3} and B = {x : x is a multiple of 5), then `A nn B` is given by
A. {3, 6, 9}
B. {5, 10, 15, 20, …}
C. {15, 30, 45, …}
D. None of these

Answer 1

Correct Answer - C
A = {x : x is a multiple of 3}
A = {x : x = 3m, `m in N`}
B = {x : x is a multiple of 5}
B = {x : x = 5n, `n in N`}
`A nn B` = {x : x is a multiple of both 3 and 5} = {15, 30, 45, …}