Definition of Radical:

A radical is a mathematical symbol (√) that represents the square root of a number. It is used to indicate the principal square root of a nonnegative number or the positive and negative roots of a complex number.

Usage:

In mathematics, radicals are commonly used when solving equations or simplifying expressions that involve square roots. They help in finding the value of an unknown variable or simplifying complex mathematical expressions.

Example:

Consider the equation x2 - 9 = 0. To solve for x, we can use radicals and rewrite the equation as x = ±√9. This implies that x could be either 3 or -3.