/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 7 Exer. 5-8: Estimate using the ch... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

Exer. 5-8: Estimate using the change of base formula. $$ \log _{9} 0.2 $$

Short Answer

Expert verified
\(\log_9{0.2} \approx -0.7322\)

Step by step solution

01

Identify the Change of Base Formula

The change of base formula is used to compute logarithms in a different base than commonly available on calculators. It is: \[ \log_b{a} = \frac{\log_c{a}}{\log_c{b}} \]where \(b\) and \(a\) are the base and number respectively, and \(c\) is any base we can compute, usually 10 or \(e\).
02

Apply the Change of Base Formula

We need to compute \(\log_9{0.2}\) using base 10. Thus, we use the formula:\[ \log_9{0.2} = \frac{\log_{10}{0.2}}{\log_{10}{9}} \]
03

Compute Logarithms with a Calculator

Use a calculator to find the values of the numerator and the denominator:- \(\log_{10}{0.2} \approx -0.69897\)- \(\log_{10}{9} \approx 0.95424\)
04

Calculate the Final Result

Substitute the values from Step 3 into the equation from Step 2:\[ \log_9{0.2} = \frac{-0.69897}{0.95424} \approx -0.7322 \]

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!

Key Concepts

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

Logarithms
Logarithms are a fundamental concept in mathematics used to solve equations involving exponential relationships. A logarithm answers the question, "To what power must a specific base be raised to obtain a given number?". For example, in the expression \( \log_b{a} = x \), the number \( a \) is the result of raising the base \( b \) to the power of \( x \).

One of the most common logarithms is the base 10 logarithm, often expressed as \( \log_{10} \). Calculators typically provide an option to compute base 10 logarithms, which can facilitate solving various problems without needing complex calculations.

Logarithms serve crucial roles in fields like science, engineering, and finance, helping in scenarios where growth rates and decay processes are involved. Understanding logarithms also paves the way for grasping more complex mathematical concepts like derivatives and integrals.
Base Conversion
Base conversion is the process of translating numbers or mathematical expressions from one base to another. This is especially important when working with logarithms where the base isn't readily available on calculators.

The change of base formula is a valuable tool for such translations. This formula allows you to compute the logarithm of any number with any base by using another base that is more convenient. The formula states:
  • \( \log_b{a} = \frac{\log_c{a}}{\log_c{b}} \)
where \( b \) and \( a \) are the base and number, and \( c \) is the base you can compute with (commonly 10 or \( e \)).

Applying this formula gives flexibility in computation and ensures that any base can be accommodated, expanding the toolkit available for tackling logarithmic problems. This approach is particularly helpful in technology and computer science, where different numeric bases play a significant role.
Mathematical Computation
Mathematical computations involving logarithms often require precision and careful execution, especially when base conversion is necessary. In the original exercise, where \( \log_9{0.2} \) was computed, using a calculator becomes imperative to achieve accurate results.

Here's a rundown of necessary steps to carry out such calculations effectively:
  • Identify the formula or method required for the calculation.
  • Use the change of base formula for dealing with uncommon bases.
  • Accurately compute logarithmic values of the numerator and denominator using a calculator.
  • Substitute these values back into your equation and simplify to find the solution.
While calculators aid with precision, understanding the underlying concepts allows you to apply the correct methods and interpret the results meaningfully. Therefore, having a solid grasp of both logarithmic functions and base conversions significantly streamlines mathematical computations.

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

Particle velocity A very small spherical particle (on the order of 5 microns in diameter) is projected into still air with an initial velocity of \(v_{0} \mathrm{~m} / \mathrm{sec}\), but its velocity decreases because of drag forces. Its velocity \(t\) seconds later is given by \(v(t)=v_{0} e^{-a t}\) for some \(a>0\), and the distance \(s(t)\) the particle travels is given by $$ s(t)=\frac{v_{0}}{a}\left(1-e^{-a t}\right) . $$ The stopping distance is the total distance traveled by the particle. (a) Find a formula that approximates the stopping distance in terms of \(v_{0}\) and \(a\). (b) Use the formula in part (a) to estimate the stopping distance if \(v_{0}=10 \mathrm{~m} / \mathrm{sec}\) and \(a=8 \times 10^{5}\).

Exer. 63-64: An economist suspects that the following data points lie on the graph of \(y=c 2^{k x}\), where \(c\) and \(k\) are constants. If the data points have three-decimal-place accuracy, is this suspicion correct? $$ \begin{aligned} &(0,-0.3),(0.5,-0.345),(1,-0.397),(1.5,-0.551) \\ &(2,-0.727) \end{aligned} $$

Urban population density An urban density model is a formula that relates the population density \(D\) (in thousands/ \(\mathrm{mi}^{2}\) ) to the distance \(x\) (in miles) from the center of the city. The formula \(D=a e^{-b x}\) for the central density \(a\) and coefficient of decay \(b\) has been found to be appropriate for many large U.S. cities. For the city of Atlanta in \(1970, a=5.5\) and \(b=0.10\). At approximately what distance was the population density 2000 per square mile?

If the pollution of Lake Erie were stopped suddenly, it has been estimated that the level y of pollutants would decrease according to the formula \(y=y_{0} e^{-0.3821 t}\), where \(t\) is the time in years and \(y_{0}\) is the pollutant level at which further pollution ceased. How many years would it take to clear \(50 \%\) of the pollutants?

When the volume control on a stereo system is increased, the voltage across a loudspeaker changes from \(V_{1}\) to \(V_{2}\), and the decibel increase in gain is given by $$ \mathrm{db}=20 \log \frac{V_{2}}{V_{1}} . $$ Find the decibel increase if the voltage changes from 2 volts to \(4.5\) volts.

See all solutions

Recommended explanations on Math Textbooks

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.