## Intermediate Algebra (12th Edition)

Published by Pearson

# Chapter 7 - Section 7.4 - Adding and Subtracting Radical Expressions - 7.4 Exercises - Page 466: 38

#### Answer

$(5+3st)\sqrt[4]{s^3t}$

#### Work Step by Step

$\bf{\text{Solution Outline:}}$ To simplify the given radical expression, $\sqrt[4]{625s^3t}+\sqrt[4]{81s^7t^5} ,$ simplify first each term by expressing the radicand as a factor that is a perfect power of the index. Then, extract the root. Finally, combine the like radicals. $\bf{\text{Solution Details:}}$ Expressing the radicand as an expression that contains a factor that is a perfect power of the index results to \begin{array}{l}\require{cancel} \sqrt[4]{625\cdot s^3t}+\sqrt[4]{81s^4t^4\cdot s^3t} \\\\= \sqrt[4]{(5)^4\cdot s^3t}+\sqrt[4]{(3st)^4\cdot s^3t} .\end{array} Extracting the roots of the factor that is a perfect power of the index results to \begin{array}{l}\require{cancel} 5\sqrt[4]{s^3t}+3st\sqrt[4]{s^3t} .\end{array} By combining like radicals, the expression above is equivalent to \begin{array}{l}\require{cancel} (5+3st)\sqrt[4]{s^3t} .\end{array}

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