Chapter 1: Problem 26
In the form \(P=P_{0} a^{t}\). Which represent exponential growth and which represent exponential decay? $$P=7 e^{-\pi t}$$
Short Answer
Expert verified
Exponential decay
Step by step solution
01
Identify the components of the given function
The function given is \(P = 7 e^{-\pi t}\). Here, the initial value \(P_0 = 7\) and the base of the exponential function is \(e^{-\pi}\). In the form \(P = P_0 a^t\), \(a\) corresponds to the base of the exponential term, which in this case is \(e^{-\pi}\).
02
Determine the value of the exponential base
The base \(a\) here is \(e^{-\pi}\). Since \(e\) is a mathematical constant approximately equal to 2.71828, \(e^{-\pi}\) means \(e\) raised to the power of \(-\pi\), which is a negative exponent.
03
Analyze the sign of the exponent
Because the exponent of \(e\) is negative (\(-\pi\)), the exponential form \(e^{-\pi}\) will result in a value that is a positive fraction less than one. This is because any positive number with a negative exponent results in a fraction.
04
Determine the type of exponential function
In exponential functions, if the base \(a\) is less than 1, the function represents exponential decay. Since \(e^{-\pi}\) is a fraction less than one, the function \(P = 7 e^{-\pi t}\) represents exponential decay.
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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 mathematical expressions that grow or decay at a constant percentage rate. They are unique in that a constant, usually greater than one, is raised to the power which varies over time. These functions can model a vast range of real-world phenomena such as population growth, radioactive decay, and even the cooling of a hot object. The general form of an exponential function is given by:
- \( P = P_0 a^t \)
- \( P \) is the final amount or value.
- \( P_0 \) is the initial amount or value.
- \( a \) is the base of the exponential function, determining the nature of growth or decay.
- \( t \) is the time variable.
Negative Exponent
In mathematics, a negative exponent signifies that the base should be moved to the denominator of a fraction. It shows how division works in exponential terms and provides a direct connection to how values decrease in exponential decay functions.For example, \( e^{- ext{value}} \) is equivalent to \( \frac{1}{e^{ ext{value}}} \). Here's what a negative exponent does:
- Makes large numbers small: A negative power of a large constant like \( e \) results in a very small number or fraction.
- Indicates inversion: It tells you to take the reciprocal of the base raised to a positive exponent.
- In exponential decay: It ensures that the exponential function decreases over time.
Mathematical Constant e
The mathematical constant \( e \), known as Euler's number, plays a critical role in exponential functions, especially those representing natural phenomena. Approximately equal to 2.71828, \( e \) is the base of natural logarithms and is pivotal in describing continuously compounding growth or decay processes.Key traits of \( e \):
- It is an irrational number, meaning it cannot be expressed as a simple fraction.
- \( e \) originates from the concept of continuously compounded interest, which is why it naturally appears in growth and decay contexts.
- The function \( e^x \) is its own derivative, making calculus operations simpler in many exponential scenarios.