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Ch. R - Review of Basic Concepts
Lial - College Algebra 13th Edition
Lial13th EditionCollege AlgebraISBN: 9780136881063Not the one you use?Change textbook
Chapter 1, Problem 85

Simplify each radical. Assume all variables represent positive real numbers. ∜(x⁴ + y⁴)

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Identify the given expression: the fourth root of the sum of two terms, written as \(\sqrt[4]{x^{4} + y^{4}}\).
Recall that the fourth root of a sum, \(\sqrt[4]{a + b}\), cannot be simplified by separating the root over addition, i.e., \(\sqrt[4]{a + b} \neq \sqrt[4]{a} + \sqrt[4]{b}\).
Since \(x\) and \(y\) are positive real numbers, consider if any terms inside the radical can be factored or simplified. Here, \(x^{4}\) and \(y^{4}\) are perfect fourth powers, but they are added, not multiplied, so factoring out a common term is not straightforward.
Recognize that \(\sqrt[4]{x^{4}} = x\) and \(\sqrt[4]{y^{4}} = y\), but because of the addition inside the radical, you cannot simplify \(\sqrt[4]{x^{4} + y^{4}}\) to \(x + y\).
Conclude that the expression \(\sqrt[4]{x^{4} + y^{4}}\) is already in its simplest radical form given the sum inside the root and the assumption that variables are positive.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Radical Expressions and Roots

Radical expressions involve roots such as square roots, cube roots, and fourth roots (∜). The nth root of a number is a value that, when raised to the nth power, gives the original number. Understanding how to interpret and manipulate these roots is essential for simplifying radical expressions.
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Properties of Exponents

Exponents indicate repeated multiplication, and their properties help simplify expressions involving powers and roots. For example, the nth root of a variable raised to the nth power simplifies to the variable itself (assuming positivity). Recognizing these properties allows simplification of radicals with variables.
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Simplification of Sums Inside Radicals

Unlike products, sums inside radicals generally cannot be separated into simpler radicals. This means expressions like ∜(x⁴ + y⁴) cannot be simplified by splitting the root over addition. Recognizing this limitation is crucial to avoid incorrect simplifications.
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