Chapter 5: Problem 54
Evaluate each expression. $$ \frac{1}{3^{-3}} $$
Short Answer
Expert verified
27
Step by step solution
01
Understand the expression
The given expression is \( \frac{1}{3^{-3}} \). It involves a fraction with a base and an exponent in the denominator.
02
Simplify the exponent
To simplify \( 3^{-3} \), recall that a negative exponent means taking the reciprocal of the base raised to the positive exponent: \[ 3^{-3} = \frac{1}{3^3} \].
03
Simplify the fraction
Substitute \( 3^{-3} \) with \( \frac{1}{3^3} \) in the original expression: \[ \frac{1}{3^{-3}} = \frac{1}{\frac{1}{3^3}} \].
04
Invert the fraction
To divide by a fraction, multiply by its reciprocal: \[ \frac{1}{\frac{1}{3^3}} = 3^3 \].
05
Calculate the power
Calculate \( 3^3 \): \[ 3^3 = 3 \times 3 \times 3 = 27 \].
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Negative Exponents
Negative exponents might look a bit scary at first, but they are actually very manageable! Let's break it down. A negative exponent indicates that you need to take the reciprocal of the base and then raise it to the positive version of that exponent.
For example, if you have \(a^{-n}\), it can be rewritten as \( \frac{1}{a^n}\). This means you flip the base into a fraction and change the exponent to a positive.
For instance, consider the expression \(3^{-3}\). To simplify this:
For example, if you have \(a^{-n}\), it can be rewritten as \( \frac{1}{a^n}\). This means you flip the base into a fraction and change the exponent to a positive.
For instance, consider the expression \(3^{-3}\). To simplify this:
- First, acknowledge that the exponent is negative, which means you take the reciprocal of 3.
- Next, raise it to the power of 3: \(3^{-3} = \frac{1}{3^3}\).
Reciprocals
Understanding reciprocals is crucial in simplifying expressions with exponents, especially negative ones. The reciprocal of a number is essentially 'flipping' it. If the number is a fraction, you swap its numerator and denominator.
For example, the reciprocal of 5 is \(\frac{1}{5}\), and the reciprocal of \(\frac{2}{3}\) is \(\frac{3}{2}\). In simpler terms, if \(a\) is a number, its reciprocal is \( \frac{1}{a} \).
When dealing with negative exponents, think in terms of reciprocals:
For example, the reciprocal of 5 is \(\frac{1}{5}\), and the reciprocal of \(\frac{2}{3}\) is \(\frac{3}{2}\). In simpler terms, if \(a\) is a number, its reciprocal is \( \frac{1}{a} \).
When dealing with negative exponents, think in terms of reciprocals:
- For instance, \(3^{-3}\) is the reciprocal of \(3^3\).
- This changes the original fraction \( \frac{1}{3^{-3}} \) to \( \frac{1}{\frac{1}{3^3}} \).
Powers of Numbers
Powers, also known as exponents, tell you how many times to multiply a number by itself. It's like repeated multiplication.
For example, \(3^3\) means you multiply 3 by itself three times: \(3 \times 3 \times 3\). The result is 27.
When calculating powers, especially with whole numbers, follow these steps:
For example, \(3^3\) means you multiply 3 by itself three times: \(3 \times 3 \times 3\). The result is 27.
When calculating powers, especially with whole numbers, follow these steps:
- Write down the base number.
- Multiply this number by itself as many times as the exponent indicates.
- So, for \(3^3\), multiply 3 by itself twice more: \(3 \times 3 = 9\) and then \(9 \times 3 = 27\).