Chapter 1: Problem 26
Evaluate each expression without using a calculator. $$ (-27)^{5 / 3} $$
Short Answer
Expert verified
The expression \((-27)^{5/3}\) evaluates to \(-243\).
Step by step solution
01
Understand the Expression
The expression is \((-27)^{\frac{5}{3}}\). This is a power operation where \(-27\) is raised to the fractional exponent \(\frac{5}{3}\).
02
Break Down the Fractional Exponent
The fractional exponent \(\frac{5}{3}\) can be understood as having two parts: the number \(5\) in the numerator indicates that the expression will be raised to the fifth power, and \(3\) in the denominator indicates taking a cube root.
03
Take the Cube Root
Start by taking the cube root of \(-27\). The cube root of \(-27\) is \(-3\), since \((-3)^3 = -27\).
04
Raise to the Fifth Power
Now, raise \(-3\) to the fifth power. Calculating \((-3)^5\) gives us:\[(-3)^5 = (-3) \times (-3) \times (-3) \times (-3) \times (-3) = -243\]
05
Combine the Steps
Combining these two steps together, we found that \[(-27)^{\frac{5}{3}} = ((-27)^{\frac{1}{3}})^5 = (-3)^5 = -243\]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Cube Root
A cube root is a mathematical function that reverses cubing a number. To find the cube root of a number, we are essentially finding a value that, when multiplied by itself three times (cubed), gives the original number. It is denoted with the symbol \( \sqrt[3]{} \).
For example, if we take the number \(-27\), the cube root is \(-3\), since \((-3) \times (-3) \times (-3) = -27\). This process involves determining which number produces \(-27\) when raised to the power of three.
Key points to remember about cube roots:
For example, if we take the number \(-27\), the cube root is \(-3\), since \((-3) \times (-3) \times (-3) = -27\). This process involves determining which number produces \(-27\) when raised to the power of three.
Key points to remember about cube roots:
- Cube roots can be extracted from negative numbers, and the result will also be a negative number, as demonstrated with \(-27\).
- Unlike square roots, there is only one real cube root for any real number, whether positive or negative.
Power Operations
Power operations are a fundamental aspect of mathematics, involving raising numbers to specific exponents. An exponent indicates how many times a number, called the base, is multiplied by itself. For instance, \((-27)^{\frac{5}{3}}\) is a power operation where the base \(-27\) is combined with a fractional exponent.
A fractional exponent, like \(\frac{5}{3}\), can be divided into two operations:
Understanding these steps can make dealing with fractional exponents much easier, as it helps break down the process into manageable operations.
A fractional exponent, like \(\frac{5}{3}\), can be divided into two operations:
- The fraction's numerator suggests raising to the power of 5.
- The denominator indicates a root, in this case, a cube root.
Understanding these steps can make dealing with fractional exponents much easier, as it helps break down the process into manageable operations.
Negative Base Powers
In mathematics, raising a negative number to a power can have interesting outcomes. A negative base raised to an even power results in a positive number because the negatives cancel each other out. Conversely, a negative base raised to an odd power remains negative, as the negative factor persists through multiplication.
Consider the expression \((-3)^5\), where the base \(-3\) is raised to the 5th power (an odd exponent). Here, the product results in a negative number, \(-243\), since multiplying \(-3\) five times preserves the sign of the base.
It's essential to:
Consider the expression \((-3)^5\), where the base \(-3\) is raised to the 5th power (an odd exponent). Here, the product results in a negative number, \(-243\), since multiplying \(-3\) five times preserves the sign of the base.
It's essential to:
- Pay attention to the behavior of negative bases when raised to different exponent values.
- Apply this logic of negative base powers when dealing with fractional exponents, as seen in \((-27)^{\frac{5}{3}}\).