Question:
Mark (✓) against the correct answer
$\sqrt{72} \times \sqrt{98}=?$
(a) 42
(b) 84
(c) 64
(d) 74
Solution:
(b) 84
$\sqrt{72} \times \sqrt{98}=\sqrt{2 \times 2 \times 2 \times 3 \times 3} \times \sqrt{2 \times 7 \times 7}=\sqrt{2 \times 2 \times 2 \times 3 \times 3 \times 2 \times 7 \times 7}=2 \times 2 \times 3 \times 7=84$