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Simplifying square roots

A square root is simplified by taking out the largest square factor under the root sign. The product rule says that the root of a product is the product of the roots, so a square factor becomes an integer in front of the root. You cannot split a sum under the root: a+b\sqrt{a + b} is not a+b\sqrt{a} + \sqrt{b}. The same rule applies when you combine like roots.

ab=a b\sqrt{ab} = \sqrt{a}\,\sqrt{b}product rule for roots
50=52\sqrt{50} = 5\sqrt{2}25 is taken out

Symbols

a, ba,\ bpositive numbers

Example

50=25⋅2=52\sqrt{50} = \sqrt{25\cdot 2} = 5\sqrt{2}.

Take out the largest square number that divides the number under the root.
Practise powers, roots and logarithms for free →

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Part of Mathematics 1T: Powers, roots and logarithms.