Chapter 1: Problem 47
Solve each equation for \(x\) . $$(a)e^{7-4 x}=6 \quad \text { (b) } \ln (3 x-10)=2$$
Short Answer
Expert verified
For (a), \( x = \frac{7-\ln(6)}{4} \). For (b), \( x = \frac{e^2 + 10}{3} \).
Step by step solution
01
Solving Part (a)
To solve the equation \( e^{7-4x} = 6 \), we start by taking the natural logarithm on both sides to remove the exponential. This gives us: \( \ln(e^{7-4x}) = \ln(6) \).
02
Apply Logarithm Properties
Using the logarithmic property \( \ln(e^y) = y \), we simplify the left side: \( 7-4x = \ln(6) \). Now the equation becomes: \( 7 - 4x = \ln(6) \).
03
Isolate x
To isolate \( x \), first subtract 7 from both sides: \( -4x = \ln(6) - 7 \). Then, divide by \(-4\) to solve for \( x \): \( x = \frac{7-\ln(6)}{4} \).
04
Solving Part (b)
For the equation \( \ln(3x-10) = 2 \), exponentiate both sides to remove the logarithm: \( e^{\ln(3x-10)} = e^2 \). This simplifies to \( 3x - 10 = e^2 \).
05
Solve for x
Add 10 to both sides to isolate the \( 3x \) term: \( 3x = e^2 + 10 \). Then divide both sides by 3 to solve for \( x \): \( x = \frac{e^2 + 10}{3} \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Natural Logarithm
The natural logarithm, denoted as \( \ln \), is a special kind of logarithm that uses the constant \( e \) (approximately 2.71828) as its base. This type of logarithm helps us solve equations involving exponential growth or decay. The natural logarithm has useful properties:
- \( \ln(1) = 0 \)
- \( \ln(e) = 1 \)
- \( \ln(e^y) = y \)
Exponential Functions
Exponential functions take the form \( f(x) = a \times e^{bx} \), where:
- \( a \) is a constant multiplier
- \( e \) is the base of the natural logarithm
- \( b \) is the rate of growth or decay
- \( x \) is the exponent variable
Solving Equations
Solving equations, especially involving exponential functions and logarithms, often requires a methodical approach. Let's break it down:
- Identify the type of equation you're dealing with – e.g., exponential, logarithmic.
- Choose the correct strategy to isolate the variable - either by applying logarithms or exponentials as shown in the solution steps.
- Simplify the equation by using logarithm properties or algebraic manipulations.