/*! 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 30 Solve the equation. $$ \log ... [FREE SOLUTION] | 91Ó°ÊÓ

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Solve the equation. $$ \log (57 x)=2+\log (x-2) $$

Short Answer

Expert verified
The solution to the equation is \( x = \frac{200}{43} \).

Step by step solution

01

Combine Logarithms

We start by using the property of logarithms that states \( \log(a) + \log(b) = \log(ab) \). The equation is \( \log(57x) = 2 + \log(x-2) \). Let's rewrite the right side using this property: \( 2 \) can also be written as \( \log 100 \) because \( 10^2 = 100 \). Now the equation becomes \( \log(57x) = \log(100) + \log(x-2) \). Using the property, we can combine the logs on the right side: \( \log(57x) = \log(100(x-2)) \).
02

Equate the Arguments of the Logarithms

Since \( \log(a) = \log(b) \) implies \( a = b \), we can equate the arguments of the logarithms: \( 57x = 100(x-2) \).
03

Expand and Rearrange Equation

Expand \( 100(x-2) \) to get \( 100x - 200 \). So, the equation \( 57x = 100x - 200 \) becomes \( 57x = 100x - 200 \). Rearranging gives us: \( 200 = 100x - 57x \).
04

Solve for x

Simplify the equation to \( 200 = 43x \). Divide both sides by 43 to isolate \( x \): \( x = \frac{200}{43} \).
05

Check for Extraneous Solutions

Since the solution should not make the arguments of the logarithms negative, check whether \( x = \frac{200}{43} \) satisfies the condition \( x - 2 > 0 \). Calculate \( \frac{200}{43} \approx 4.65 \), which is greater than 2. Therefore, the solution is valid.

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Key Concepts

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

Properties of Logarithms
Logarithms have various properties that make them incredibly useful for simplifying and solving equations. One key property is that you can combine or split logarithms by using the rules for multiplication or division. - For example, when you have the expression \( \log(a) + \log(b) \), you can combine these into a single logarithm, \( \log(ab) \). This becomes very handy in solving equations, as you can see in our problem.- In this specific equation \( \log(57x) = 2 + \log(x-2) \), the number 2 alone is not a logarithm, but it can be rewritten as a power of 10, making \( 2 = \log(100) \) because \( 10^2 = 100 \).With this knowledge, we can rearrange equations to either simplify the calculation or make it possible to isolate and solve for a variable. This property is essential for both combining logarithms and eventually canceled terms on both sides of the equation.
Equating Arguments in Logarithms
To solve logarithmic equations, it is often necessary to compare the arguments from both sides, assuming the logarithmic bases are the same. The essential property used here is that if two logarithms with the same base are equal, their arguments must be equal.- This property is expressed as: if \( \log(a) = \log(b) \), then \( a = b \). - For our problem, after we have combined the logarithms using the properties, the equation \( \log(57x) = \log(100(x-2)) \) directly implies that the arguments \( 57x \) and \( 100(x-2) \) must be equal.By equating these arguments, we effectively remove the logarithms from the equation, simplifying it to solve for the unknown variable "x." This step transforms a potentially complex logarithmic equation into a more manageable form.
Solving Linear Equations
After equating the logarithmic arguments, you often end up with a simple linear equation. Solving linear equations involves isolating the variable on one side of the equation to find its value.- In our specific problem, after equating \( 57x = 100(x-2) \), we expanded and rearranged the equation. This led us to: \( 57x = 100x - 200 \).- Rearrange to bring all terms involving \( x \) to one side. Simplifying gives \( 200 = 100x - 57x \).- This further reduces to \( 200 = 43x \).- Finally, divide both sides by 43 to solve for \( x \). This yields \( x = \frac{200}{43} \). Solving for "x" using basic algebraic steps is crucial once the logarithmic mechanism simplifies your equation to this point.
Checking for Extraneous Solutions
When dealing with logarithms, one critical step is ensuring that any solution you find does not result in taking the logarithm of a negative number or zero. Conditions for logarithms usually require their arguments to be positive.- Once you have the solution from a simplified equation, check to see that it makes all original logarithmic expressions valid.- For our solution \( x = \frac{200}{43} \), approximate it to check feasibility. This approximates to 4.65.- Ensure that substituting this value into the equation does not cause any term like \( x-2 \) to be negative: \( x-2 = \frac{200}{43} - 2 \) which equals about 2.65, greater than zero.By performing this check, you confirm that the solution does not create any undefined expressions and verify the solution's accuracy. Always remember this last check to ensure your solutions are real and applicable.

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Most popular questions from this chapter

Sketch the graph of \(f\). $$ f(x)=\log _{2} \sqrt[3]{x} $$

For manufacturers of computer chips, it is important to consider the fraction \(F\) of chips that will fail after \(t\) years of service. This fraction can sometimes be approximated by the formula \(F=1-e^{-c t}\), where \(c\) is a positive constant. (a) How does the value of \(c\) affect the reliability of a chip? (b) If \(c=0.125\), after how many years will \(35 \%\) of the chips have failed?

Certain learning processes may be illustrated by the graph of an equation of the form \(f(x)=a+b\left(1-e^{-c}\right)\), where \(a, b\), and \(c\) are positive constants. Suppose a manufacturer estimates that a new employee can produce five items the first day on the job. As the employee becomes more proficient, the daily production increases until a certain maximum production is reached. Suppose that on the \(n\)th day on the job, the number \(f(n)\) of items produced is approximated by $$ f(n)=3+20\left(1-e^{-0.1 n}\right) . $$ (a) Estimate the number of items produced on the fifth day, the ninth day, the twenty-fourth day, and the thirtieth day. (b) Sketch the graph of \(f\) from \(n=0\) to \(n=30\). (Graphs of this type are called learning curves and are used frequently in education and psychology.) (c) What happens as \(n\) increases without bound?

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