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91Ó°ÊÓ

Use the change-of-base rule to find an approximation for each logarithm. $$\log _{100} 83$$

Short Answer

Expert verified
\( \log_{100} 83 \approx 0.9595 \)

Step by step solution

01

Identify the Change of Base Formula

The change of base formula for logarithms is \( \log_b a = \frac{\log_c a}{\log_c b} \), where \( c \) is any positive number other than 1. A common choice for \( c \) is 10 or \( e \).
02

Apply the Change of Base Formula

Using the change of base formula, we can express \( \log_{100} 83 \) as \( \frac{\log_{10} 83}{\log_{10} 100} \).
03

Calculate \( \log_{10} 83 \)

Using a calculator, compute \( \log_{10} 83 \). This is approximately 1.919.
04

Calculate \( \log_{10} 100 \)

Since 100 is \( 10^2 \), \( \log_{10} 100 = 2 \).
05

Perform the Division

Divide the result from Step 3 by the result from Step 4: \( \frac{1.919}{2} \approx 0.9595 \).

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Understanding Logarithms
Logarithms can initially seem like a complex mathematical concept, but they are quite useful in many areas of science and everyday calculations. Simply put, a logarithm asks the question: "To what power must we raise a certain base number to obtain another number?" For example, in the expression \( \log_{10} 100 \), we are asking "10 raised to what power gives us 100?" The answer is 2, because \( 10^2 = 100 \).

Logarithms are the inverse operations of exponentiation, meaning they undo what exponentiation does. Instead of multiplying repeatedly, they allow us to "undo" the multiplication by finding the power. This makes logarithms very practical when dealing with exponential scales, such as in scientific calculations, audio systems, and earthquake magnitude measurements.

Utilizing the change-of-base formula is one application of log operations, facilitating the computation of logarithms with different bases using more familiar ones.
Exploring the Base 10 Logarithm
The base 10 logarithm, often simply called the "common logarithm," is widely used. In mathematics, it is denoted as \( \log_{10} \) or sometimes just \( \log \) when the context is clear. This base is so popular because it aligns with the decimal system we use every day.

Common logarithms are particularly useful in situations where the properties of decimals are advantageous. For instance:
  • Data logarithms make charts like semilog graphs possible.
  • Model relationships showing exponential growth or decay, such as population growth or radioactive decay.
  • Enhance computational ease as base 10 logarithms often have simpler integer results.
In the exercise above, finding \( \log_{10} 83 \) and \( \log_{10} 100 \) involves common logarithms. The latter is straightforward since \( 100 \) is a direct power of 10, simplifying to 2, as seen in the solution.
The Role of Mathematical Approximation
Mathematical approximation is a powerful tool that simplifies complex or cumbersome calculations into more digestible numbers. When exact values are not readily accessible or necessary, approximation provides a practical solution.

In the context of the logarithmic exercise, we needed to evaluate \( \log_{10} 83 \), a number that does not result in a neat integer logarithmic value. Instead of detailed calculations, a tool like a calculator is used to provide an approximate value (here, it was 1.919). This kind of approximation is acceptable in everyday arithmetic where very precise values are unnecessary.
  • Approximations make complex calculations manageable and quicker.
  • They are essential in fields requiring rapid data processing or when measuring uncertainties, such as engineering and physics.
  • Though they may slightly reduce precision, they retain enough accuracy for many practical purposes.
This exercise shows the change-of-base formula as a practical application of approximation, achieving a final result of approximately 0.9595.

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Most popular questions from this chapter

Solve each problem. World Population Growth since 2000 , world population in millions closely fits the exponential function $$ y=6079 e^{0.0126 x} $$ where \(x\) is the number of years since 2000 . (Image can't copy) (a) The world population was about 6555 million in 2006 . How closely does the function approximate this value? (b) Use this model to estimate the population in 2010 . (c) Use this model to predict the population in 2025 . (d) Explain why this model may not be accurate for 2025 .

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