Chapter 9: Problem 33
Find a good bound for the maximum value of the given expression, given that \(c\) is in the stated interval. Answers may vary depending on the technique used. $$ \left|\frac{e^{c}}{c+5}\right| ;[-2,4] $$
Short Answer
Expert verified
The maximum value of the expression is approximately 6.
Step by step solution
01
Identify the Range of the Expression
The given expression is \( \left|\frac{e^c}{c+5}\right| \) and we need to evaluate this for \( c \in [-2, 4] \). Since the range extends from negative to positive, we should consider the behavior of both the numerator and the denominator across this range.
02
Analyze the Numerator, \(e^c\)
The function \( e^c \) is an exponential function that increases rapidly. Within the range \([-2,4]\), \(e^c\) will take its minimum value at \(c = -2\) and maximum value at \(c = 4\). Compute these values: \( e^{-2} \approx 0.1353 \) and \( e^4 \approx 54.598 \).
03
Analyze the Denominator, \(c+5\)
The function \( c+5 \) is a linear function. Within the range \([-2,4]\), it takes its minimum value at \(c = -2\) and maximum value at \(c = 4\). Compute these values: \(-2+5 = 3\) and \(4+5 = 9\).
04
Calculate the Maximum and Minimum of \(\left|\frac{e^c}{c+5}\right|\)
The extreme values of the expression can be checked using the extreme values of \( e^c \) and \( c+5 \):1. Maximum value: \( \frac{e^4}{5+4} = \frac{54.598}{9} \approx 6.066 \).2. Minimum value: \( \frac{e^{-2}}{5-2} = \frac{0.1353}{3} \approx 0.0451 \).However, because the expression is always positive, we focus on finding the largest value which is at \(c = 4\).
05
Final Bound for the Expression
After examining the changes of both the numerator and the denominator, the expression attains its maximum value when \( c = 4 \). This maximum value is at \( \frac{54.598}{9} \approx 6.066 \). Thus, a good bound for the maximum value of the expression is approximately 6.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Exponential Functions
Exponential functions are a type of mathematical function in which a constant base is raised to a variable exponent. In the equation \( e^c \), \( e \) (approximately equal to 2.718) is the base and \( c \) is the exponent. Exponential functions are known for their rapid growth or decay, depending on the value of the exponent.
Key characteristics of exponential functions include:
Key characteristics of exponential functions include:
- As \( c \) increases, \( e^c \) increases rapidly due to the property of exponential growth.
- When \( c \) is negative, \( e^c \) produces a value between 0 and 1, indicating decay.
Interval Analysis
Interval analysis in this context refers to examining the range of possible values for \( c \) and assessing the function's behavior across this span. The interval \([-2, 4]\) defines the boundaries within which we analyze the given expression \( \left|\frac{e^c}{c+5}\right| \).
This process involves:
This process involves:
- Identifying the extreme points, which are \( -2 \) and \( 4 \), to establish the minimum and maximum behavior of the expression.
- Studying how both the numerator \( e^c \) and the denominator \( c+5 \) change as \( c \) varies within this interval.
Numerator and Denominator Behavior
Understanding the behavior of the numerator \( e^c \) and the denominator \( c+5 \) is crucial in optimizing expressions.
For the numerator, \( e^c \):
For the numerator, \( e^c \):
- This part of the expression increases exponentially, meaning it can grow very large very quickly, especially towards the end of our interval at \( c = 4 \).
- At \( c = -2 \), \( e^c \)'s value is significantly smaller, contributing to smaller overall outcomes in the expression.
- This linear component adds a constant adjustment to the variable \( c \). As \( c \) rises, so does the denominator, extending from 3 to 9 over the interval.
- A larger \( c+5 \) diminishes the value of the fraction, as a bigger denominator results in a smaller final value.