Question

If $A=\{1,2,4,5\}$ and $B=\{a,b\}$ Find the total number of relations from $A$ to $B$.

Answer 1

Given:$A=\{1,2,4,5\}$ and $B=\{a,b\}$

Number of relations from $A$ to $B=2^{NumberofelementsinA\times B}$

$=2^{n\left(A\right)\times n\left(B\right)}$

$=2^{4\times 2}=2^8=256$