Chapter 6: Problem 1
Write each number in exponential form with base 3 . a. 81 b. 27 c. 9 d. \(\frac{1}{3}\) e. \(\frac{1}{9}\) f. 1
Short Answer
Expert verified
81 is \(3^4\), 27 is \(3^3\), 9 is \(3^2\), \(\frac{1}{3}\) is \(3^{-1}\), \(\frac{1}{9}\) is \(3^{-2}\), and 1 is \(3^0\).
Step by step solution
01
Recognize the Base
We need to express each number in the form of powers of 3. This means if we have a number like 81, we should be thinking about what power of 3 results in 81.
02
Express 81 as a Power of 3
81 can be expressed as a power of 3. We need to calculate how many 3s are multiplied to get 81.\[81 = 3^4\]So, 81 is \(3^4\).
03
Express 27 as a Power of 3
27 is another number we need to express with base 3.\[27 = 3^3\]Therefore, 27 is \(3^3\).
04
Express 9 as a Power of 3
Next, we determine how to express 9 in exponential form with base 3.\[9 = 3^2\]Thus, 9 is \(3^2\).
05
Express \(\frac{1}{3}\) as a Power of 3
We need to write \(\frac{1}{3}\) as a power of 3. Recognize that \(\frac{1}{3}\) is the reciprocal of 3.\[\frac{1}{3} = 3^{-1}\]Hence, \(\frac{1}{3}\) is \(3^{-1}\).
06
Express \(\frac{1}{9}\) as a Power of 3
Now, let's express \(\frac{1}{9}\) as a power of 3. Since \(9 = 3^2\), its reciprocal is:\[\frac{1}{9} = 3^{-2}\]So, \(\frac{1}{9}\) is \(3^{-2}\).
07
Express 1 as a Power of 3
Finally, any number raised to the power of 0 is 1.\[1 = 3^0\]Therefore, 1 is \(3^0\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Powers of Numbers
Exponents are a simple yet powerful tool in mathematics. When we talk about the power of a number, we're referring to how many times a number (known as the base) is multiplied by itself. For example, when we say 3 raised to the power of 4, written as \(3^4\), we mean \(3 \times 3 \times 3 \times 3\). This repeated multiplication is what gives us exponential growth, a concept central to many math applications.
- Exponential form is helpful for simplifying expressions and calculations.
- They are written as \(b^n\), where \(b\) is the base and \(n\) is the exponent.
- Exponents show how many times the base is used as a factor.
Base 3
Numbers can be expressed using a variety of bases; however, base 3 is particularly interesting. In base 3, each number is represented as a power of 3. Let’s explore this concept further. For example, the number 81 is \(3^4\) when written in base 3. This means multiplying four 3s together: \(3 \times 3 \times 3 \times 3 = 81\).
- Base 3 is just one way to express numbers exponentially.
- It is similar to other bases like base 10 or base 2; the base number is the one that is repeated as a factor.
- Common examples include 81 as \(3^4\), 27 as \(3^3\), 9 as \(3^2\), and so on.
Reciprocal
A reciprocal is simply the inverse of a number. If you have a number and multiply it with its reciprocal, you get 1. For example, the reciprocal of 3 is \(\frac{1}{3}\). In the context of exponents, taking the reciprocal is similar to changing the sign of the exponent.
- Reciprocal of \(n\) is \(\frac{1}{n}\).
- Multiplying a number by its reciprocal results in 1.
- In exponents, the reciprocal changes the exponent from positive to negative.
Negative Exponents
Negative exponents indicate the reciprocal of a number raised to a positive exponent. For instance, \(3^{-1}\) represents \(\frac{1}{3}\). Instead of multiplying, you are essentially dividing 1 by the base raised to the positive equivalent of the negative exponent.
- A negative exponent represents a reciprocal.
- \(b^{-n}\) is equivalent to \(\frac{1}{b^n}\).
- It simplifies expressions by allowing division to be represented alongside multiplication.