Chapter 7: Problem 18
Evaluate expression. \((-32)^{1 / 5}\)
Short Answer
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Step by step solution
01
- Understand the problem
The problem requires the evaluation of the expression \((-32)^{1 / 5}\). This means finding the fifth root of -32.
02
- Define the fifth root
The fifth root of a number \((x)\) is another number \((y)\) such that \((y^5 = x)\). In this case, we are looking for a number \((y)\) such that \((y^5 = -32)\).
03
- Calculate the fifth root
Since \((-2)^5 = -2 \times -2 \times -2 \times -2 \times -2 = -32\), the fifth root of \(-32\) is \(-2\).
04
- Write the final answer
Therefore, \((-32)^{1 / 5} = -2\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Exponents
Exponents are a way to express repeated multiplication of the same number. For example, if we have the expression \(2^3\), it means \(2 \times 2 \times 2\). Here, 2 is the base and 3 is the exponent (also referred to as the power). In general, \(a^n\) means you multiply \(a\), the base, by itself \(n\) times.
Exponent rules are essential for simplifying expressions:
- Any number raised to the power of 1 is itself: \(a^1 = a\)
- Any number raised to the power of 0 is 1: \(a^0 = 1\) (as long as \(a \eq 0\))
- Multiplying powers with the same base adds the exponents: \(a^m \times a^n = a^{m+n}\)
- Raising a power to another power multiplies the exponents: \((a^m)^n = a^{m \times n}\) Understanding these rules can make it easier to handle more complex problems involving exponents.
Exponent rules are essential for simplifying expressions:
- Any number raised to the power of 1 is itself: \(a^1 = a\)
- Any number raised to the power of 0 is 1: \(a^0 = 1\) (as long as \(a \eq 0\))
- Multiplying powers with the same base adds the exponents: \(a^m \times a^n = a^{m+n}\)
- Raising a power to another power multiplies the exponents: \((a^m)^n = a^{m \times n}\) Understanding these rules can make it easier to handle more complex problems involving exponents.
Negative Numbers
Understanding negative numbers is crucial when working with exponents and roots. A negative number is simply a number that is less than zero. It is often represented with a minus sign (e.g., -3).
In our example, we are dealing with \(-32 \). It's important to note that raising a negative number to an odd power will result in a negative number, while raising it to an even power results in a positive number:
- \((-2)^3 = -8 \) (since 3 is odd)
- \((-2)^4 = 16 \) (since 4 is even)
This concept is fundamental in evaluating expressions like \((-32)^{1/5} \), where we are essentially looking for the fifth root of a negative number.
In our example, we are dealing with \(-32 \). It's important to note that raising a negative number to an odd power will result in a negative number, while raising it to an even power results in a positive number:
- \((-2)^3 = -8 \) (since 3 is odd)
- \((-2)^4 = 16 \) (since 4 is even)
This concept is fundamental in evaluating expressions like \((-32)^{1/5} \), where we are essentially looking for the fifth root of a negative number.
Radical Expressions
Radical expressions involve roots. In mathematics, a radical (or root) symbol \(\sqrt{}\) is used to denote the root of a number. The most common is the square root, but we also use other roots like cube roots (\(\sqrt[3]{}\)) and in our example, the fifth root.
The general form of a radical expression is \(\sqrt[n]{a} \), which means finding the number \(b\) such that \(b^n = a\).
Specifically, for \((-32)^{1/5} \), we are looking for a number that, when raised to the power of 5, equals -32. Since \((-2)^5 = -32 \), the fifth root of -32 is -2.
Key points to remember:
- The index number (\(n\)) tells you which root to take.
- For positive numbers, there can be both positive and negative roots (e.g., \(\sqrt[4]{16} = 2\) and \(-2)\) but for negative bases, only odd roots are valid, e.g., \(\sqrt[5]{-32} = -2\). Understanding these will help you solve radical expressions more effectively.
The general form of a radical expression is \(\sqrt[n]{a} \), which means finding the number \(b\) such that \(b^n = a\).
Specifically, for \((-32)^{1/5} \), we are looking for a number that, when raised to the power of 5, equals -32. Since \((-2)^5 = -32 \), the fifth root of -32 is -2.
Key points to remember:
- The index number (\(n\)) tells you which root to take.
- For positive numbers, there can be both positive and negative roots (e.g., \(\sqrt[4]{16} = 2\) and \(-2)\) but for negative bases, only odd roots are valid, e.g., \(\sqrt[5]{-32} = -2\). Understanding these will help you solve radical expressions more effectively.