Surd

A surd is an irrational number that is expressed as a root of a rational number. Surds are used to represent exact values of roots that cannot be simplified into whole numbers or finite decimals.

Example

$\sqrt{3}$ and $\sqrt{5}$ are surds because they cannot be simplified to rational numbers. However, $\sqrt{4}$ is not a surd because it simplifies exactly to $2$.

See Also

• Irrational Number
• Radical
• Rationalization