Chapter 5: Problem 89
Use the change-of-base rule to find an approximation for each logarithm. $$\log _{5} 10$$
Short Answer
Expert verified
\(\log_5 10 \approx 1.43067\).
Step by step solution
01
Understanding the Change-of-Base Formula
The change-of-base formula allows us to evaluate logarithms using a different base, usually 10 or e, which are easier to compute with calculators. The formula is: \[\log_b a = \frac{\log_c a}{\log_c b}\]where \(c\) is the new base. Common choices for \(c\) are 10 (common logarithm) or \(e\) (natural logarithm).
02
Apply the Change-of-Base Formula
We need to find \(\log_5 10\). Using the change-of-base formula with base 10, we write:\[\log_5 10 = \frac{\log_{10} 10}{\log_{10} 5}\]
03
Calculate Each Logarithm Using a Calculator
Using a calculator, we find: \(\log_{10} 10 = 1\) because 10 raised to the power of 1 is 10, and \(\log_{10} 5 \approx 0.69897\).
04
Compute the Approximation
Now, substitute the values into the change-of-base formula:\[\log_5 10 = \frac{1}{0.69897} \approx 1.43067\] So, \(\log_5 10 \approx 1.43067\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Logarithms
Logarithms are a mathematical operation that help us deal with exponential relationships. They are essentially the inverse of exponentiation. This means if you know a result in an exponential equation and you want to find one of the exponents, you would use logarithms. For example, in the equation \( 10^x = 100 \), we can find \( x \) by using logarithms.We have different bases for logarithms:
- Logarithm base 10: This is known as the common logarithm. Often written as \( \log \).
- Logarithm base \( e \): This is known as the natural logarithm. Represented as \( \ln \).
- Logarithm base 2: Used in computing, known as binary logarithm.
Common Logarithm
The common logarithm is simply a logarithm with a base of 10. It's widely used in science and engineering because it simplifies expressions with powers of 10. When you see \( \log \) without a specified base, it's usually assumed to be base 10.One main property of the common logarithm is:
- \( \log_{10} 10 = 1 \): because 10 to the power of 1 is 10.
Natural Logarithm
Natural logarithms use the base \( e \), where \( e \approx 2.718 \). This base, \( e \), arises naturally in the context of continuous growth or decay, making natural logarithms very important in calculus and complex mathematics.Whenever you see \( \ln \), it denotes a logarithm with base \( e \). Some key characteristics include:
- The natural logarithm of \( e \), \( \ln e = 1 \), because \( e^1 = e \).
- They are useful in solving differential equations and situations involving compound interest.