Chapter 1: Problem 15
In Exercises \(10-15,\) give \(\lim _{x \rightarrow-\infty} f(x)\) and \(\lim _{x \rightarrow+\infty} f(x)\). $$f(x)=25 e^{0.08 x}$$
Short Answer
Expert verified
\( \lim_{x \rightarrow -\infty} f(x) = 0 \) and \( \lim_{x \rightarrow +\infty} f(x) = \infty \).
Step by step solution
01
Understand the Function
The given function is \( f(x) = 25 e^{0.08x} \). This is an exponential function where the base of the exponent is \( e \), a mathematical constant approximately equal to 2.71828. The exponent \( 0.08x \) means that the function grows or decays exponentially based on the value of \( x \).
02
Analyze the Limit as x Approaches -Infinity
When we consider \( \lim_{x \rightarrow -\infty} f(x) \), we are looking at what happens to the function as \( x \) becomes very large in the negative direction. As \( x \to -\infty \), the term \( 0.08x \) tends to \(-\infty\) and \( e^{0.08x} \to e^{-\infty} \), which equals \( 0 \). Therefore, \( f(x) \to 25 \cdot 0 = 0 \).
03
Analyze the Limit as x Approaches +Infinity
When we consider \( \lim_{x \rightarrow +\infty} f(x) \), we are analyzing what happens as \( x \) becomes very large in the positive direction. Here, \( 0.08x \) tends towards \(+\infty\), and so \( e^{0.08x} \to e^{\infty} \), which approaches infinity. Thus, \( f(x) \to 25 \times \infty = \infty \).
04
Summarize the Limits
Based on the calculations, the limits can be summarized as follows: \( \lim_{x \rightarrow -\infty} f(x) = 0 \) and \( \lim_{x \rightarrow +\infty} f(x) = \infty \). This indicates that as \( x \to -\infty \), the function approaches 0, and as \( x \to +\infty \), it grows without bound.
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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 fundamental in mathematics and have wide-ranging applications. One defining feature of an exponential function, such as \( f(x) = 25 e^{0.08x} \), is that the independent variable \( x \) appears in the exponent. This setup results in a unique type of growth or decay that's different from linear or quadratic functions.
- Growth behavior is often rapid, meaning small changes in \( x \) can cause large changes in \( f(x) \).
- The base of the exponent \( e \) is a special constant approximately equal to 2.71828. It is known as Euler's number.
Behavior at Infinity
The behavior of a function as it approaches infinity is significant in calculus. For the function \( f(x) = 25 e^{0.08x} \), examining the behavior at infinity involves looking at what happens as \( x \) becomes very large or very small.
- As \( x \to +\infty \), \( 0.08x \) also goes to infinity, and \( e^{0.08x} \) grows exponentially without bound, so the function \( f(x) = 25 e^{0.08x} \) will also reach towards infinity.
- Conversely, as \( x \to -\infty \), \( 0.08x \) trends towards \(-\infty\), making \( e^{0.08x} = e^{-\infty} \approx 0\). Hence, \( f(x) \approx 25 \times 0 = 0 \).
Limits of Functions
The concept of limits is one of the cornerstones of calculus. Limits help us understand the behavior of functions as inputs approach a certain value. For the function \( f(x) = 25 e^{0.08x} \), we evaluated limits as \( x \) approaches positive and negative infinity.
- When \( x \to -\infty \), \( \, \lim_{x \to -\infty} f(x) = 0 \), meaning the function gets closer and closer to zero.
- When \( x \to +\infty \), \( \, \lim_{x \to +\infty} f(x) = \infty \), indicating the function's value increases indefinitely.