/*! 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 45 Use the properties of logarithms... [FREE SOLUTION] | 91Ó°ÊÓ

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Use the properties of logarithms to expand the expression as a sum, difference, and/or constant multiple of logarithms. (Assume all variables are positive.) $$\ln 4 x$$

Short Answer

Expert verified
The expanded form of \(\ln 4x\) is 1.386 + \(\ln x\).

Step by step solution

01

Apply the Logarithmic Multiplication Property

The property of logarithms that states the logarithm of a product is equal to the sum of the logarithms is applied. This equation becomes \(\ln 4x = \ln 4 + \ln x\).
02

Simplify Logarithmic Expression

The expression \(\ln 4\) is a constant, since the logarithm of 4 to the base e is approximately 1.386. So, the equation becomes 1.386 + \(\ln x\).

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Key Concepts

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

Logarithmic Multiplication Property
The logarithmic multiplication property is one of the fundamental rules that helps us work with logarithms more conveniently. This property states that the logarithm of a product is the sum of the logarithms of the individual factors. In mathematical terms, if you have two numbers, say \(a\) and \(b\), their product can be expressed using the logarithmic multiplication property as follows:
  • \(\log(a \cdot b) = \log a + \log b\)
This property is extremely useful when we are trying to simplify or manipulate logarithmic expressions.
For example, when expanding \(\ln 4x\), this property allows us to split it into two separate and more manageable logarithmic terms. Here, it translates to \(\ln 4 + \ln x\).
This separation is helpful because each term can then be handled individually, making calculations easier.
Expanding Logarithmic Expressions
The process of expanding logarithmic expressions involves breaking them down into simpler components using the property of the logarithms. When expanding, you should keep in mind the properties such as the one for multiplication, division, or powers.
  • For multiplication: \(\ln(ab) = \ln a + \ln b\)
  • For division: \(\ln\left(\frac{a}{b}\right) = \ln a - \ln b\)
  • For powers: \(\ln(a^b) = b\ln a\)
In the given exercise, expanding \(\ln 4x\) uses the multiplication property. The expression can be separated into \(\ln 4\) and \(\ln x\).
Simplifying these components, especially when constants like \(\ln 4\) are involved, further clarifies the expression into simpler terms, here turning into a sum of a constant and a variable term.
By learning to expand expressions, you enhance your skill in managing and solving more complex logarithmic problems.
Logarithmic Properties in Precalculus
Logarithmic properties are essential tools in precalculus that prepare you for tackling algebraic functions involving logarithms. These properties simplify complex equations and provide a deeper understanding of their behavior.
  • Basic Properties: These include the multiplication, division, and power rules mentioned previously.
  • Change of Base Formula: This is another useful property which lets you write logarithms in terms of logs of a different base: \(\log_b a = \frac{\log_k a}{\log_k b}\).
Developing a solid grasp of these properties can significantly aid in your further mathematical education.
They allow for flexibility in solving equations and simplifying expressions, critical for comprehensive understanding in math-related fields.
Practice involves both recognizing when these properties can be applied and using them effectively to simplify and solve different types of logarithmic expressions.

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Most popular questions from this chapter

A logistic growth model has the form ________.

Find a logarithmic equation that relates \(y\) and \(x .\) Explain the steps used to find the equation. $$ \begin{array}{|l|c|c|c|c|c|c|} \hline x & 1 & 2 & 3 & 4 & 5 & 6 \\ \hline y & 1 & 1.587 & 2.080 & 2.520 & 2.924 & 3.302 \\ \hline \end{array} $$

A cup of water at an initial temperature of \(78^{\circ} \mathrm{C}\) is placed in a room at a constant temperature of \(21^{\circ} \mathrm{C}\). The temperature of the water is measured every 5 minutes during a half-hour period. The results are recorded as ordered pairs of the form \((t, T),\) where \(t\) is the time (in minutes) and \(T\) is the temperature (in degrees Celsius). \(\left(0,78.0^{\circ}\right),\left(5,66.0^{\circ}\right),\left(10,57.5^{\circ}\right),\left(15,51.2^{\circ}\right)\) \(\left(20,46.3^{\circ}\right),\left(25,42.4^{\circ}\right),\left(30,39.6^{\circ}\right)\) (a) The graph of the model for the data should be asymptotic with the graph of the temperature of the room. Subtract the room temperature from each of the temperatures in the ordered pairs. Use a graphing utility to plot the data points \((t, T)\) and \((t, T-21)\). (b) An exponential model for the data \((t, T-21)\) is given by \(T-21=54.4(0.964)^{t} .\) Solve for \(T\) and graph the model. Compare the result with the plot of the original data. (c) Take the natural logarithms of the revised temperatures. Use a graphing utility to plot the points \((t, \ln (T-21))\) and observe that the points appear to be linear. Use the regression feature of the graphing utility to fit a line to these data. This resulting line has the form \(\ln (T-21)=a t+b\). Solve for \(T,\) and verify that the result is equivalent to the model in part (b). (d) Fit a rational model to the data. Take the reciprocals of the \(y\) -coordinates of the revised data points to generate the points \(\left(t, \frac{1}{T-21}\right)\) Use a graphing utility to graph these points and observe that they appear to be linear. Use the regression feature of a graphing utility to fit a line to these data. The resulting line has the form \(\frac{1}{T-21}=a t+b\) Solve for \(T,\) and use a graphing utility to graph the rational function and the original data points. (e) Why did taking the logarithms of the temperatures lead to a linear scatter plot? Why did taking the reciprocals of the temperatures lead to a linear scatter plot?

Automobiles are designed with crumple zones that help protect their occupants in crashes. The crumple zones allow the occupants to move short distances when the automobiles come to abrupt stops. The greater the distance moved, the fewer g's the crash victims experience. (One \(g\) is equal to the acceleration due to gravity. For very short periods of time, humans have withstood as much as 40 g's.) In crash tests with vehicles moving at 90 kilometers per hour, analysts measured the numbers of g's experienced during deceleration by crash dummies that were permitted to move \(x\) meters during impact. The data are shown in the table. A model for the data is given by \(y=-3.00+11.88 \ln x+(36.94 / x),\) where \(y\) is the number of g's. $$ \begin{array}{|c|c|} \hline x & \text { g's } \\ \hline 0.2 & 158 \\ 0.4 & 80 \\ 0.6 & 53 \\ 0.8 & 40 \\ 1.0 & 32 \\ \hline \end{array} $$ (a) Complete the table using the model. $$ \begin{array}{|l|l|l|l|l|l|} \hline x & 0.2 & 0.4 & 0.6 & 0.8 & 1.0 \\ \hline y & & & & & \\ \hline \end{array} $$ (b) Use a graphing utility to graph the data points and the model in the same viewing window. How do they compare? (c) Use the model to estimate the distance traveled during impact if the passenger deceleration must not exceed \(30 \mathrm{~g}\) 's. (d) Do you think it is practical to lower the number of g's experienced during impact to fewer than \(23 ?\) Explain your reasoning.

The model $$t=16.625 \ln \left(\frac{x}{x-750}\right), \quad x>750$$ approximates the length of a home mortgage of \(\$ 150,000\) at \(6 \%\) in terms of the monthly payment. In the model, \(t\) is the length of the mortgage in years and \(x\) is the monthly payment in dollars. (a) Use the model to approximate the lengths of a \(\$ 150,000\) mortgage at \(6 \%\) when the monthly payment is \(\$ 897.72\) and when the monthly payment is \(\$ 1659.24\) (b) Approximate the total amounts paid over the term of the mortgage with a monthly payment of \(\$ 897.72\) and with a monthly payment of \(\$ 1659.24 .\) (c) Approximate the total interest charges for a monthly payment of \(\$ 897.72\) and for a monthly payment of \(\$ 1659.24\) (d) What is the vertical asymptote for the model? Interpret its meaning in the context of the problem.

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