/*! 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 66 Solve the logarithmic equation a... [FREE SOLUTION] | 91Ó°ÊÓ

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Solve the logarithmic equation algebraically. Approximate the result to three decimal places.\(\ln 4 x=1\)

Short Answer

Expert verified
The solution to the equation is \(x = 0.679\) to three decimal places.

Step by step solution

01

Convert the Logarithm to Exponential Form

Recall that the natural logarithm \(\ln a = b\) can be rewritten in exponential form as \(e^b = a\). Applying this property to the given equation \(\ln 4 x = 1\), the equation can be converted to \(4x = e^1\).
02

Solve for x

To isolate \(x\), divide both sides of the equation by 4, which results in \(x = \frac{e^1}{4}\). Here, \(e^1\) is the mathematical constant \(e\) to the power of 1. Since anything to the power of 1 is itself, it simplifies to \(x = \frac{e}{4}\).
03

Approximate to Three Decimal Places

Now we need to use a calculator to find the decimal approximation to the value of \(e\) divided by 4 to three decimal places. So, \(x = \frac{e}{4} = 0.679\) to three decimal places

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Key Concepts

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

Understanding the Natural Logarithm
The natural logarithm, denoted as \(\ln\), is a powerful tool in mathematics, not just a mere symbol. At its core, \(\ln\) pertains to logarithms with base \(e\), approximately equal to 2.71828, which is known as Euler's number. Unlike base 10 logarithms, the natural logarithm is often used in calculations involving continuous growth, such as compound interest, population growth, and even in solving differential equations.
In any expression like \(\ln a = b\), the logarithm answers the question: To what power must \(e\) be raised, to obtain \(a\)? This unique attribute makes it particularly handy in converting into exponential forms, an essential step in solving logarithmic equations. Let's see how this transformation aids in solving the original equation \(\ln 4x = 1\) by transforming it into something more manageable.
The characteristics of the natural logarithm allow us to seamlessly convert into exponential form, which leads us into the next concept. This ability to interchange between forms is invaluable when tackling equations that initially appear complex.
Converting to Exponential Form
Transforming logarithmic equations into their exponential counterparts is an essential technique to make solving easier. By converting, we reveal another layer to the problem that is often simpler to handle. When you see \(\ln 4x = 1\), you're essentially asking: What power must \(e\) be raised to, to get \(4x\)?
Conveniently, the expression \(\ln a = b\) transforms into \(e^b = a\). For instance, in our problem, it's converted to \(4x = e^1\). By setting up the equation in this way, the natural logarithm simplifies and becomes a straightforward expression of \(x\).
Breaking it down further:
  • Convert \(\ln 4x = 1\) to \(4x = e^1\).
  • Recognize that \(e^1 = e\) since any number raised to the power of 1 is itself.
This shift from logarithmic to exponential form is not just a mathematical manipulation; it's a revelation that unveils the path to solving the equation efficiently.
Achieving Decimal Approximation
Once we have a simplified expression like \(x = \frac{e}{4}\), our goal shifts from pure algebra to practical approximation, essential in real-world applications where exact values are impractical. Decimal approximation allows us to represent real numbers, like the constant \(e\), in a finite number of digits.
Using a calculator or computational tool, we approximate \(e\) to about 2.71828. Then, plugging this into the expression gives \(\frac{2.71828}{4}\). This calculation results in \(0.67957\), which we round to three decimal places, resulting in \(0.679\).
  • Use a calculator to evaluate \(\frac{e}{4}\).*
  • Round the number to three decimal places.
  • This renders our result suitable for quick comprehension and application in further problems or contexts.
Decimal approximations are vital for ensuring answers are concise and practical, especially in cases requiring precision such as scientific measurements.

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Most popular questions from this chapter

A grape has a pH of \(3.5\), and baking soda has a pH of \(8.0\). The hydrogen ion concentration of the grape is how many times that of the baking soda?

Aged Population The table shows the projected U.S. populations \(P\) (in thousands) of people who are 85 years old or older for several years from 2010 to \(2050 . \quad\) (Source: U.S. Census Bureau)$$ \begin{array}{|c|c|} \hline \text { Year } & 85 \text { years and older } \\ \hline 2010 & 6123 \\ \hline 2015 & 6822 \\ \hline 2020 & 7269 \\ \hline 2025 & 8011 \\ \hline 2030 & 9603 \\ \hline 2035 & 12,430 \\ \hline 2040 & 15,409 \\ \hline 2045 & 18,498 \\ \hline 2050 & 20,861 \\ \hline \end{array} $$(a) Use a graphing utility to create a scatter plot of the data. Let \(t\) represent the year, with \(t=10\) corresponding to 2010 . (b) Use the regression feature of a graphing utility to find an exponential model for the data. Use the Inverse Property \(b=e^{\ln b}\) to rewrite the model as an exponential model in base \(e\). (c) Use a graphing utility to graph the exponential model in base \(e\). (d) Use the exponential model in base \(e\) to estimate the populations of people who are 85 years old or older in 2022 and in 2042 .

Super Bowl Ad Cost The table shows the costs \(C\) (in millions of dollars) of a 30 -second TV ad during the Super Bowl for several years from 1987 to \(2006 .\) (Source: TNS Media Intelligence)$$ \begin{array}{|c|c|} \hline \text { Year } & \text { Cost } \\ \hline 1987 & 0.6 \\ \hline 1992 & 0.9 \\ \hline 1997 & 1.2 \\ \hline 2002 & 2.2 \\ \hline 2006 & 2.5 \\ \hline \end{array} $$(a) Use a graphing utility to create a scatter plot of the data. Let \(t\) represent the year, with \(t=7\) corresponding to \(1987 .\) (b) Use the regression feature of a graphing utility to find an exponential model for the data. Use the Inverse Property \(b=e^{\ln b}\) to rewrite the model as an exponential model in base \(e\). (c) Use a graphing utility to graph the exponential model in base \(e\). (d) Use the exponential model in base \(e\) to predict the costs of a 30 -second ad during the Super Bowl in 2009 and in 2010 .

The average monthly sales \(y\) (in billions of dollars) in retail trade in the United States from 1996 to 2005 can be approximated by the model \(y=-22+117 \ln t, \quad 6 \leq t \leq 15\) where \(t\) represents the year, with \(t=6\) corresponding to 1996\. (Source: U.S. Council of Economic Advisors) (a) Use a graphing utility to graph the model. (b) Use a graphing utility to estimate the year in which the average monthly sales first exceeded \(\$ 270\) billion. (c) Verify your answer to part (b) algebraically.

Women's Heights The distribution of heights of American women (between 30 and 39 years of age) can be approximated by the function \(p=0.163 e^{-(x-64.9)^{2} / 12.03}, \quad 60 \leq x \leq 74\) where \(x\) is the height (in inches) and \(p\) is the percent (in decimal form). Use a graphing utility to graph the function. Then determine the average height of women in this age bracket. (Source: U.S. National Center for Health Statistics)

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