Chapter 12: Problem 47
Solve. $$ \log _{3} x=4 $$
Short Answer
Expert verified
The value of \( x \) is 81.
Step by step solution
01
Understand the Logarithmic Equation
The equation given is \( \log_{3} x = 4 \). Here, \( \log_{3} x \) represents a logarithmic function with base 3, and the equation implies that \( 3 \) raised to some power results in \( x \). The goal is to find the value of \( x \).
02
Convert the Logarithm to an Exponential Form
To solve the logarithmic equation, convert it into an exponential equation. The logarithmic equation \( \log_{3} x = 4 \) means that the base, 3, raised to the power of 4 gives \( x \). This can be written as \( 3^4 = x \).
03
Calculate the Exponential Result
Now evaluate \( 3^4 \). Since \( 3^4 \ = \ 3 \times 3 \times 3 \times 3 \ = 81 \), the value of \( x \) is 81.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Logarithmic Functions
Logarithmic functions are a fundamental concept in mathematics that deal with the inverse of exponential functions. In a logarithmic function, you are essentially asking the question: "To what power must a given base be raised to produce a certain number?" The general form of a logarithmic function is \[\log_b (y) = x,\]where \(b\) is the base, \(y\) is the number for which you want to find the logarithm, and \(x\) is the exponent. Here's how it works:
- If \(b^x = y\), then \(\log_b (y) = x\).
- Logarithms answer the question "How many of one number do we multiply to get another number?"
- Common logarithms include the natural logarithm (\(\log_e\), where \(e\) is approximately 2.718) and the common logarithm (\(\log_{10}\)).
Exponential Equations
Exponential equations are equations in which variables appear in the exponent. These are critical for solving logarithmic problems since they inherently describe the relationship between a base and its logarithmic exponent. The general exponential equation looks like:\[b^y = x,\]where \(b\) is the base, \(y\) is the exponent, and \(x\) is the result of the exponential operation. Key aspects of exponential equations include:
- They help translate logarithmic expressions into a form that can be computed or simplified.
- Exponential equations often require manipulation of exponents through operations like multiplication, division, or taking roots to solve them.
- Solving exponential equations often necessitates the application of logarithms as inverse functions to isolate the exponent.
Converting Logarithms to Exponents
Converting logarithmic expressions into their exponential counterparts is a powerful technique for solving problems that involve logarithms. This conversion relies on the fundamental relationship between logarithms and exponents. Given a logarithmic equation of the form \[\log_b (y) = x,\]you can express it as an exponential equation:\[b^x = y.\]To carry out the conversion, keep these points in mind:
- Identify the base \(b\) and the logarithmic result \(x\) from the given logarithmic function.
- Switch the logarithmic form \(\log_b y = x\) to its equivalent exponential form \(b^x = y\).
- This step often simplifies the problem, making it easier to solve for the unknown variable.