if a Ð N such that aN={ax:x Ð N}, describe the set 3N ∩ 7N - Maths - Sets

Question

if a Ð„ N such that aN={ax:x Ð„ N}, describe
the set 3N ∩ 7N

Lakshmy · Accepted Answer

x = 1,2,3,4,
So the set aN becomes {a,2a,3a }
That means 3N = {3 21, ,42, } and 7N = {7,14,21, 42, }
So 3N â„¦ 7N = {21,42, } = 21N
Similarly aN â„¦ bN =[ LCM (a,b)]N
Hope u understood!

if a Є N such that aN={ax:x Є N}, describe the set 3N ∩ 7N