Mathematics
Grade 11
15 min
Add and subtract radical expressions
Add and subtract radical expressions
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1
Introduction & Learning Objectives
Learning Objectives
Identify like and unlike radical terms based on their index and radicand.
Simplify radical expressions by factoring out perfect squares, cubes, or other nth powers.
Combine like radical terms by adding or subtracting their coefficients.
Add and subtract expressions containing multiple radical terms, some of which require simplification first.
Simplify and combine radical expressions that include variables in the radicand.
Apply the distributive property to multiply a monomial by a binomial containing radicals.
You know that 3x + 5x = 8x, but what about 3√2 + 5√2? 🤔 It works almost exactly the same way!
This tutorial will teach you how to add and subtract radical expressions. You'll learn that this process is very similar to combining like terms in...
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Key Concepts & Vocabulary
TermDefinitionExample
Radical ExpressionAn expression that contains a root (square root, cube root, etc.). The symbol for the root is called the radical sign (√).5√3, √x, and 2∛(7y) are all radical expressions.
RadicandThe number or expression found inside the radical sign.In the expression √18, the radicand is 18.
IndexThe small number to the left of the radical sign that indicates which root is being taken.In the expression ∛8, the index is 3. If no index is written, it is assumed to be 2 (a square root).
Like RadicalsRadical terms that have the exact same index and the exact same radicand.7√5 and -2√5 are like radicals. However, 7√5 and 7∛5 are not (different indices).
Simplest Radical FormA radical is in its simplest form when the radicand contains no perfect square factors (or perfec...
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Core Formulas
Combining Like Radicals
a√[n]{x} + b√[n]{x} = (a + b)√[n]{x}
To add or subtract like radicals, you add or subtract their coefficients (the numbers in front of the radical) and keep the radical part the same. This is analogous to combining like terms such as 2x + 3x = 5x.
Product Rule for Radicals
√[n]{ab} = √[n]{a} * √[n]{b}
This rule is essential for simplifying radicals. It allows you to break down a radicand into its factors and separate them into different radicals, which helps in finding and extracting perfect nth powers.
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Challenging
Expand and simplify the expression: (2√3 - √6)(√3 + 4√6)
A.6 + 7√18 - 24
B.-18 + 21√2
C.30 + 7√18
D.-18 - 7√2
Challenging
Simplify the expression, assuming a, b ≥ 0: √(72a³b⁴) - a√(18ab⁴)
A.3ab²√2a
B.9ab²√a
C.0
D.3ab²√a
Challenging
Which of the following expressions is equivalent to 2√108 - 3√48 + √3?
A.0
B.2√63
C.-√3
D.√3
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