# 1.6 Roots and Radicals

• Principal nth Root • Simplifying Radicals • Using a Calculator • Imaginary Numbers

At times, we have to find the square root of a number, or maybe some other root of a number, such as a cube root. This means we must find a number that when squared, or cubed, and so on equals some given number. For example, to find the square root of 9, we must find a number that when squared equals 9. In this case, either 3 or  is an answer. Therefore, either 3 or  is a square root of 9 since  and 

To have a general notation for the square root and have it represent one number, we define the principal square root of a to be positive if a is positive and represent it by  This means  and not 

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