Square and Cube Root Laws

Mathematics — Second Preparatory

The square root of a square

When the expression under the root is a square of an unknown sign, the root gives the absolute value.
For example, √(4x²) = √4 × √(x²) = 2|x|.
If x = −3, then 2|x| = 6, which is the same as √(4 × 9) = √36 = 6.

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