Chapter 9: Problem 7
Write each as an exponential equation. See Example 1. $$ \log _{9} x=4 $$
Short Answer
Expert verified
The exponential equation is \( x = 6561 \).
Step by step solution
01
Understand Logarithmic Form
The given logarithmic equation is \( \log_{9} x = 4 \). This represents the power to which the base 9 must be raised to obtain the number \( x \).
02
Write the Exponential Form
By definition of logarithms, \( \log_{b} a = c \) means \( b^{c} = a \). Here, \( b = 9 \), \( a = x \), and \( c = 4 \). Therefore, rewrite the equation as \( 9^4 = x \).
03
Simplify the Exponentiation
Calculate the value of \( 9^4 \). Compute by multiplying: \( 9 \times 9 = 81 \) and then \( 81 \times 81 = 6561 \). So, \( 9^4 = 6561 \).
04
Write the Final Exponential Equation
Substitute the calculated value back into the equation from Step 2 to express it as \( x = 6561 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Logarithmic Form
A logarithmic form is a way to express the relationship between three numbers. It tells us that a number is the exponent to which a base must be raised to yield another number. In the context of our problem, the expression \( \log_{9} x = 4 \) tells us that to get \( x \), the base 9 should be raised to the power 4. This is a useful concept because logarithms help us solve problems involving exponential growth or decay by simplifying the exponentiation process.
Understanding logarithmic form is crucial because it acts as a bridge between multiplication and exponentiation. It allows for easy manipulation of exponential equations, which can otherwise be cumbersome. The expression \( \log_{b} a = c \) indicates that the base \( b \) raised to the power \( c \) equals \( a \). This form can be translated directly into an exponential equation, aiding in solving real-world problems.
Understanding logarithmic form is crucial because it acts as a bridge between multiplication and exponentiation. It allows for easy manipulation of exponential equations, which can otherwise be cumbersome. The expression \( \log_{b} a = c \) indicates that the base \( b \) raised to the power \( c \) equals \( a \). This form can be translated directly into an exponential equation, aiding in solving real-world problems.
Exponential Form
The exponential form of an equation reveals how many times a base number is multiplied by itself. In relation to the original exercise where we have \( \log_{9} x = 4 \), converting this logarithmic form into exponential form gives us \( 9^4 = x \). This step is vital because, in performance calculations, mechanical systems, and many scientific models, expressions in exponential form allow for more straightforward computation.
- By interpreting \( 9^4 \) as an exponential expression, we understand it as multiplying 9 by itself four times.
- This simplification transforms complex logarithmic relationships into usable arithmetic operations.
Solving Equations
Solving equations, particularly those involving exponents, often requires transforming them into a more familiar or workable form. In our example, when encountering \( \log_{9} x = 4 \), converting to the exponential form \( 9^4 = x \) simplifies the solving process. By doing this, we eliminate the logarithm, leaving us with a more straightforward calculation.
Identifying how to transition between forms is crucial because:
Identifying how to transition between forms is crucial because:
- It makes equations easier to solve analytically or manually without advanced technology.
- It also offers a cleaner method to evaluate problems where logarithms are inconvenient.
Exponentiation
Exponentiation is a mathematical operation that represents repeated multiplication of a base. For example, in our equation from the original exercise, \( 9^4 \) is the exponentiation of 9 raised to the power of 4. This means that 9 is multiplied by itself exactly four times to achieve the result.
Subsequently calculating \( 9^4 \) involves:
Subsequently calculating \( 9^4 \) involves:
- First multiplying 9 by itself to get 81.
- Then multiplying 81 by itself to arrive at 6,561.