Chapter 7: Problem 85
Use rational expressions to write as a single radical expression. $$ \sqrt[3]{y} \cdot \sqrt[5]{y^{2}} $$
Short Answer
Expert verified
\( \sqrt[3]{y} \cdot \sqrt[5]{y^2} = \sqrt[15]{y^{11}} \)
Step by step solution
01
Express each radical using rational exponents
The expression given is \( \sqrt[3]{y} \cdot \sqrt[5]{y^{2}} \). We first convert each radical into an expression with a rational exponent. For \( \sqrt[3]{y} \), this becomes \( y^{1/3} \), and for \( \sqrt[5]{y^{2}} \), this becomes \( y^{2/5} \). Thus, the expression is now \( y^{1/3} \cdot y^{2/5} \).
02
Use the property of exponents to combine terms
Recall the property \( a^m \cdot a^n = a^{m+n} \). Applying this property, we combine the terms: \( y^{1/3} \cdot y^{2/5} = y^{1/3 + 2/5} \).
03
Simplify the exponent expression
To add the exponents \( \frac{1}{3} \) and \( \frac{2}{5} \), we find a common denominator. The least common denominator of 3 and 5 is 15. Convert \( \frac{1}{3} = \frac{5}{15} \) and \( \frac{2}{5} = \frac{6}{15} \). Add these to get \( \frac{5}{15} + \frac{6}{15} = \frac{11}{15} \). Thus, the expression is \( y^{11/15} \).
04
Convert back to radical notation
Finally, convert the expression back from a rational exponent to radical notation. \( y^{11/15} \) can be written as \( \sqrt[15]{y^{11}} \). Therefore, the expression \( \sqrt[3]{y} \cdot \sqrt[5]{y^{2}} \) simplifies to \( \sqrt[15]{y^{11}} \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Rational Exponents
Rational exponents are a way to express roots and powers in the same notation. They provide a convenient method to switch between radical forms and exponential forms. For example, instead of writing cube root \( \sqrt[3]{x} \), we can express it as \( x^{1/3} \). A rational exponent is simply a fraction.
- The numerator indicates the power. In \( x^{m/n} \), the variable is raised to the power \( m \).
- The denominator indicates the root. \( n \) instructs us to take the \( n \)-th root of the base.
Properties of Exponents
Properties of exponents allow us to manipulate expressions involving powers efficiently. One important property is the product of powers property, \( a^m \cdot a^n = a^{m+n} \), which helps combine like bases. This is crucial when solving expressions with multiple radicals or exponents. Another useful property is the power of a power property, which states \((a^m)^n = a^{m\cdot n}\). When dealing with fractional exponents,
- The base stays the same.
- Add the exponents together when multiplying like bases. This means if you have \( y^{1/3} \cdot y^{2/5} \), you add the exponents (\( 1/3 \) and \( 2/5 \)) together.
Simplifying Radical Expressions
Simplifying radical expressions is about making them as straightforward as possible while retaining their mathematical value. The goal is to express a complex radical in its simplest form. This often involves converting radicals to rational exponents, using exponent properties to simplify, and then converting back to radical form if needed.
- Start with converting radicals to rational exponents for ease of calculation.
- Use properties of exponents to add, subtract, or otherwise manipulate the exponents.
- Finally, if the problem requires, convert back to radical form for the simplest representation.