Question

Let * be a ‘binary’ operation on N given by a*b = LCM (a, b) for all a, b∈N. Find 5 * 7.

Answer 1

$a \: * \: b \: = \: LCM \: ( \: a \: , \: b \: ) \\ \\ 5\: * \: 7 = \: ? \\ \\5 \: * \: 7\: = \: LCM \: ( \: 5 \: , \: 7 \: ) \\ \\ \large \color{blue} \boxed{5\: * \: 7 = \: 35}$