JAMB 1995 · UME · Q22

If $a * b = +\sqrt{ab}$ , evaluate $2 * (12 * 27)$ .

Worked solution (try it first)

Work out the bracket first: $12 * 27 = \sqrt{12 \times 27}$
$= \sqrt{324}$
$= 18$ .
Then $2 * 18 = \sqrt{2 \times 18}$
$= \sqrt{36}$
$= 6$ , option C.