Question

The identity of the binary operation * defined by $a\ast b=\frac{ab}{4}$ is equal to.

• A. 1
• B. 2
• C. 4

Answer 1

The correct option is C 4

If e is the identity of a binary operation *, then
a * e = e * a = a

Here, $a\ast e=\frac{ae}{4}$

Thus, $\frac{ae}{4}=a$

$\Rightarrow e=4$