Chapter 4: Problem 15
Evaluate the expression. (a) \(\log _{3} 3\) (b) \(\log _{3} 1\) (c) \(\log _{3} 3^{2}\)
Short Answer
Expert verified
(a) 1, (b) 0, (c) 2
Step by step solution
01
Understanding Logarithms
To evaluate a logarithm, such as \( \log_{3} b \), we need to find the power to which the base (3) must be raised to get the number \( b \).
02
Evaluating \( \log_{3} 3 \)
Since \( 3^{1} = 3 \), \( \log_{3} 3 = 1 \) because 3 must be raised to the power of 1 to result in 3.
03
Evaluating \( \log_{3} 1 \)
Any non-zero number raised to the power of 0 is 1. Therefore, \( 3^{0} = 1 \), so \( \log_{3} 1 = 0 \).
04
Evaluating \( \log_{3} 3^{2} \)
The expression \( \log_{3} 3^{2} \) can be rewritten as \( 2 \log_{3} 3 \). Since we found earlier that \( \log_{3} 3 = 1 \), it follows that \( 2 \log_{3} 3 = 2 \times 1 = 2 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Evaluating Logarithms
Logarithms help us understand the concept of exponents in reverse. To evaluate a logarithm like \( \log_{3} b \), we are essentially asking: "To what power must 3 be raised, so that the result is \( b \) ?" This inverse relationship makes it a powerful tool in mathematics. For example, in the exercise given:
- \( \log_{3} 3 \) equals 1 because you need to raise 3 to the power of 1 to get 3. Indeed, \( 3^{1} = 3 \).
- For \( \log_{3} 1 \), the result is 0 because 3 raised to the power of 0 gives you 1: \( 3^{0} = 1 \).
- In the case of \( \log_{3} 3^{2} \), this simplifies to 2 because 3 to the power of 2 gives you 9, but since we have 3 squared within a logarithm, it results in \( 2 \log_{3} 3 \) which calculates to 2.
Logarithmic Properties
Logarithms possess several unique properties that greatly simplify complex calculations. When dealing with expressions involving multiple logarithmic elements, these properties are essential:
- Product Property: The logarithm of a product can be expressed as the sum of the logarithms of the individual factors: \( \log_b(mn) = \log_b m + \log_b n \).
- Quotient Property: The logarithm of a quotient is the difference of the logarithms: \( \log_b(\frac{m}{n}) = \log_b m - \log_b n \).
- Power Property: When an exponent is present, such as in \( \log_b (m^n) \), it can be simplified by bringing the exponent in front: \( n \log_b m \). This was used in evaluating \( \log_3 3^2 \), transforming it into \( 2 \log_3 3 \).
Logarithmic Functions
Logarithmic functions are fundamental in mathematics, representing the concept of logarithms as a function. They are the opposite of exponential functions. While exponential functions are of the form \( y = b^x \), logarithmic functions are \( y = \log_b x \). This inverse relationship is crucial in various scientific and engineering contexts.The graph of a logarithmic function \( y = \log_b x \) has distinct characteristics:
- The graph passes through the point (1,0) because \( \log_b 1 = 0 \) for any base \( b \).
- It approaches negative infinity as \( x \) approaches 0 from the right but never touches the y-axis, showing it is undefined for non-positive values of \( x \). This makes the x-axis an asymptote.
- The growth is gradual, indicating that logarithmic functions increase more slowly compared to linear or polynomial functions.