EXPLANATION:
Given set A = { 1,2,3}
n(A) = 3
Let the n(B) be n
Total number of relations from A to B = 2^(3×n) =2^3n
According to the given problem
Total relations are = 512
⇛2^3n = 512
⇛2^3n = 2⁹
If bases are equal then exponents must be equal
⇛3n = 9
⇛n = 9/3
⇛n = 3
So, Number of elements in the set B = 3
