Question

Express as a mixed surd: $\sqrt{80}$

• A. $6400$
• B. $4\sqrt{5}$
• C. $5\sqrt{4}$
• D. $40$

Answer 1

Answer: (B)

$4\sqrt{5}$

A surd having a rational co-efficient other than unity is called a mixed surd.

$\sqrt{80}=\sqrt{4^2\times 5}=\sqrt{4^2}\times \sqrt{5}=4\sqrt{5}$