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๐Ÿ”ŸElementary Algebra Unit 9 Review

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9.2 Simplify Square Roots

๐Ÿ”ŸElementary Algebra
Unit 9 Review

9.2 Simplify Square Roots

Written by the Fiveable Content Team โ€ข Last updated September 2025
Written by the Fiveable Content Team โ€ข Last updated September 2025
๐Ÿ”ŸElementary Algebra
Unit & Topic Study Guides

Square roots are a fundamental concept in algebra, unlocking new ways to solve equations and simplify expressions. They allow us to work with numbers that aren't perfect squares, opening up a world of possibilities in math and science.

Understanding the properties of square roots is crucial for tackling more complex problems. By mastering these rules, you'll be able to simplify radical expressions, rationalize denominators, and solve equations involving square roots with confidence.

Properties of Square Roots

Product property of square roots

  • States $\sqrt{a \cdot b} = \sqrt{a} \cdot \sqrt{b}$
  • Allows splitting the product of two numbers under a square root into the product of their individual square roots ($\sqrt{18} = \sqrt{9 \cdot 2} = \sqrt{9} \cdot \sqrt{2} = 3\sqrt{2}$)
  • When simplifying square roots, look for perfect square factors under the square root
    • Perfect squares are numbers expressed as the product of an integer multiplied by itself (1, 4, 9, 16, 25, 36, 49, 64, 81, 100)
  • If a number under a square root is not a perfect square, factor out any perfect square factors ($\sqrt{50} = \sqrt{25 \cdot 2} = \sqrt{25} \cdot \sqrt{2} = 5\sqrt{2}$)
  • This property is fundamental in simplifying radical expressions

Quotient property of square roots

  • States $\sqrt{\frac{a}{b}} = \frac{\sqrt{a}}{\sqrt{b}}$, where $b \neq 0$
  • Allows splitting a fraction under a square root into a fraction of the individual square roots ($\sqrt{\frac{9}{16}} = \frac{\sqrt{9}}{\sqrt{16}} = \frac{3}{4}$)
  • When simplifying square roots with fractions, look for perfect square factors in both the numerator and denominator
    • If both the numerator and denominator are perfect squares, simplify each square root separately ($\sqrt{\frac{36}{49}} = \frac{\sqrt{36}}{\sqrt{49}} = \frac{6}{7}$)
  • If the numerator or denominator is not a perfect square, factor out any perfect square factors ($\sqrt{\frac{18}{25}} = \sqrt{\frac{9 \cdot 2}{25}} = \frac{\sqrt{9} \cdot \sqrt{2}}{\sqrt{25}} = \frac{3\sqrt{2}}{5}$)
  • This property is useful in rationalization of denominators

Order of operations with square roots

  • When simplifying expressions containing square roots, follow the standard order of operations (PEMDAS)
    1. Parentheses: Simplify expressions inside parentheses first
    2. Exponents: Evaluate exponents and roots (including square roots)
    3. Multiplication and Division: Perform multiplication and division from left to right
    4. Addition and Subtraction: Perform addition and subtraction from left to right
  • Simplify square roots before performing other operations ($2 + \sqrt{18} - 3 \cdot \sqrt{4} = 2 + 3\sqrt{2} - 3 \cdot 2 = 2 + 3\sqrt{2} - 6$)
  • Combine like terms, if possible, after simplifying square roots
    • Like terms have the same variable and exponent ($2\sqrt{3} + 5\sqrt{3} = 7\sqrt{3}$)
  • Simplify any remaining operations according to the order of operations ($4 + 2\sqrt{6} - 3 \cdot (1 + \sqrt{9}) = 4 + 2\sqrt{6} - 3 \cdot (1 + 3) = 4 + 2\sqrt{6} - 3 \cdot 4 = 4 + 2\sqrt{6} - 12 = -8 + 2\sqrt{6}$)

Additional Concepts in Square Root Simplification

  • The square root function is represented as f(x) = โˆšx and is the inverse of the squaring function
  • Surds are irrational numbers expressed using root symbols
  • Conjugates are used in rationalization to eliminate square roots in denominators
    • For example, to rationalize 1/(โˆš2 + 1), multiply by (โˆš2 - 1)/(โˆš2 - 1)