ACT Preparation / Unit 7 ACT 0610 short lesson, about 20 seconds
Square Roots and Simplifying Radicals
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The idea
The principal square root, written √a, is the non-negative root. For non-negative a and b, √(ab) = √a · √b, so a radical is simplified by factoring out perfect squares.
In practice
√72 = √36 · √2 = 6√2.
Where people slip
√25 is 5, not ±5. And a root does not split over a sum: √(9 + 16) is 5, not 7.
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