If $a=2$then the value of $-6a^2$is

The correct option is B

(b) $-24$

The given algebraic expression can be written as

$-6a^2=-6\times a\times a$

Substituting $a=2,$ we get :

$$\begin{gathered} -6a^2=-6\times 2\times 2 \\ =-12\times 2 \\ =-24 \end{gathered}$$

Hence , Option (b) is the correct answer