Question

State which of the following are pure surds and mixed surds:

$\sqrt{21}$

• A. Pure surd
• B. Mixed surd
• C. Not a surd
• D. None of the above

Answer 1

The correct option is A Pure surd

A surd in which the whole of the rational number is under the radical sign and makes the radicand, is called pure surd.
In other words a surd having no rational factor except unity is called a pure surd or complete surd
Thus,$\sqrt{2}1$ is a pure surd.