# Solve this

Question:

$\sqrt{10} \times \sqrt{15}=?$

(i) $\sqrt{25}$

(ii) $5 \sqrt{6}$

(iii) $6 \sqrt{5}$

(iv) None of these

Solution:

$\sqrt{10} \times \sqrt{15}$

$=\sqrt{2 \times 5} \times \sqrt{3 \times 5}$

$=\sqrt{2} \times \sqrt{5} \times \sqrt{3} \times \sqrt{5} \quad[\sqrt{a b}=\sqrt{a} \times \sqrt{b}]$

$=5 \times \sqrt{2 \times 3}$

$=5 \sqrt{6}$

Hence, the correct answer is option (ii).