Question

Simplify $\sqrt{128}$.

• A. $8\times \sqrt{5}$
• B. $8\times \sqrt{3}$
• C. $7\times \sqrt{2}$
• D. $8\times \sqrt{2}$

Answer 1

The correct option is D

$8\times \sqrt{2}$

Rule:

$\sqrt{x}\times \sqrt{y}=\sqrt{xy}$

OR

$\sqrt{xy}=\sqrt{x}\times \sqrt{y}$

Let $xy=128$

$\Rightarrow \sqrt{128}=\sqrt{64}\times \sqrt{2}$

$\Rightarrow \sqrt{128}=8\times \sqrt{2}$