Question

If $A-\left\{2,4,3\right\},B-\left\{7,8,9\right\}$,then $n\left(A\times B\right)$ is equal to

Answer 1

Answer: 9

$A\times B=\left\{\left(2,7\right),\left(2,8\right)\left(2,9\right),\left(4,7\right),\left(4,8\right),\left(4,9\right),\left(5,7\right),\left(5,8\right),\left(5,9\right)\right\}$
$n\left(A\times B\right)=n\left(A\right).n\left(B\right)=3\times 3=9$