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

Short Answer

Expert verified
A logarithmic equation that can be derived from the given data is \(y = \log_{1.515} x\).

Step by step solution

01

Understanding the logarithmic function

In general, formulas that have the form \(y = a \log_b x\) are called logarithmic functions, where: \(a\) is the coefficient, \(b\) is the base of the logarithm, \(x\) is the argument of the logarithm, and \(y\) is the result. From the given table, we have several values for \(x\) and \(y\). We can take two of these points for further calculations, preferably the ones that would return the simplest calculations.
02

Setting up an equation

Let's take \(x = 1, y = 1\) and \(x = 2, y = 1.587\). We can set up two equations using these points: \(1 = a \log_b 1\) and \(1.587 = a \log_b 2\). From the first equation, we know that \(\log\) of any number at base \(b\) is always 0 except when the number is 1. Therefore, we can conclude that \(a = 1\). Substitute this back into the second equation to solve for \(b\) by taking antilog.
03

Solving for base of logarithm

Substituting \(a = 1\) in the second equation, we get \(1.587 = \log_b 2\). To solve for \(b\), we rewrite the equation in exponential form: \(b = 2^{1/1.587}\). Using a calculator for accuracy, this gives \(b \approx 1.515\).
04

Verification

We should confirm this logarithmic model by checking it against a few other values given in the table. If the values confirm, this model of logarithmic function is correct for the relationship between \(x\) and \(y\).

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Key Concepts

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

Logarithmic Functions
Imagine you have a mysterious box where you put a number and the box tells you how many times you need to multiply a special number to get the one you put in. In the world of mathematics, this box is called a logarithmic function. It's a way to reverse the process of exponentiation, which means finding out what exponent you need to raise a certain base to, in order to get another number (the argument).

Logarithmic functions have a standard form of \( y = a \log_b(x) \), where 'a' is the coefficient that stretches or shrinks the graph, 'b' is the base of the logarithm telling us the special number to multiply, 'x' is the number you're curious about (the argument), and 'y' gives you the power you need to raise 'b' to get 'x'.

Understanding logarithmic functions can be quite handy. They help us to solve problems about exponential growth like population growth, radioactive decay, and even the decibels of sound. The exercise given is a classic example of how these functions are used to model real-world situations based on a set of data points.
Exponential Form
Turning a logarithm into an exponent can be like translating a secret code into a language we understand. To make sense of logarithmic equations, sometimes we need to translate them into their equivalent exponential form. The exponential form is what you get when you switch a logarithmic equation like \( y = \log_b(x) \) into the form \( b^y = x \).

In the given exercise, once the coefficient 'a' is understood to be 1 from the first piece of data, the second piece of data is used to solve the logarithmic equation for the base 'b'. Rewriting the logarithmic function in exponential form makes the problem of finding 'b' much simpler. We use the new form to evaluate 'b' using the properties of exponents, making the rest of the problem a matter of arithmetic or calculator work.
Solving Logarithms
Breaking down logarithmic equations may sometimes feel like solving a puzzle. To find the value of 'y' or the base 'b', we must unlock the relationship between the components in the logarithm. One of the fundamental tools to solve logarithms is understanding that \(\log_b(1)=0\), no matter what the value of the base 'b' is (unless 'b' is 1).

When given two sets of data points, we can create two equations and begin our detective work to solve for unknowns. The first point often simplifies the equation due to the nature of logarithms, leading to a quick revelation of the coefficient 'a'. With 'a' in hand, the focus shifts to discovering 'b', which when done correctly, reveals the pattern connecting 'x' and 'y'. It's important for students to practice this process to feel comfortable transitioning between the logarithmic and exponential views of these relationships.
Logarithm Base
The base of a logarithm is the foundation. It's the number that's consistently used as the multiplier in the exponential equation equivalent. Just as different countries may use different currencies, different logarithmic equations can use different bases. Common bases include 10 for common logarithms and 'e' (approximately 2.718) for natural logarithms.

In the context of the exercise solution, once the coefficient 'a' was determined to be 1, the base 'b' becomes the priority. By converting the remaining logarithmic equation into its exponential counterpart, we are left with a simple equation that gives us 'b' when solved. The base 'b' is critical because it defines the growth rate in the modeled situation. The appropriate base turns raw data into an understandable pattern, allowing predictions and further insights into the behavior of the system being modeled.

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Most popular questions from this chapter

The number \(V\) of computers infected by a computer virus increases according to the model \(V(t)=100 e^{4.6052 t}\), where \(t\) is the time in hours. Find the number of computers infected after (a) 1 hour, (b) 1.5 hours, and (c) 2 hours.

The values \(y\) (in billions of dollars) of U.S. currency in circulation in the years \(\begin{array}{lllll}2000 & \text { through } 2007 & \text { can be } & \text { modeled } & \text { by }\end{array}\) \(y=-451+444 \ln t, 10 \leq t \leq 17,\) where \(t\) represents the year, with \(t=10\) corresponding to 2000 . During which year did the value of U.S. currency in circulation exceed \$690 billion? (Source: Board of Governors of the Federal Reserve System)

Solve the exponential equation algebraically. Approximate the result to three decimal places. $$e^{3 x}=12$$

A sport utility vehicle that costs $$\$ 23,300$$ new has a book value of $$\$ 12,500$$ after 2 years. (a) Find the linear model \(V=m t+b\). (b) Find the exponential model \(V=a e^{k t}\) (c) Use a graphing utility to graph the two models in the same viewing window. Which model depreciates faster in the first 2 years? (d) Find the book values of the vehicle after 1 year and after 3 years using each model. (e) Explain the advantages and disadvantages of using each model to a buyer and a seller.

The sales \(S\) (in thousands of units) of a new CD burner after it has been on the market for \(t\) years are modeled by \(S(t)=100\left(1-e^{k t}\right) .\) Fifteen thousand units of the new product were sold the first year. (a) Complete the model by solving for \(k\). (b) Sketch the graph of the model. (c) Use the model to estimate the number of units sold after 5 years.

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