1Cademy - Radical Sign

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Square of a Number

Concept

Radical Sign

The radical sign is the symbol $\sqrt{\phantom{x}}$ used to denote the principal (positive) square root of a number. For instance, $\sqrt{25} = 5$ because $5$ is the positive number whose square is $25$ . Although both $5$ and $-5$ satisfy $n^2 = 25$ , the radical sign by convention refers only to the non-negative root. This notation provides a compact way to indicate the square-root operation without writing it out in words.