Chapter 8: Problem 28
In each of Exercises 23-34, derive the Maclaurin series of the given function \(f(x)\) by using a known Maclaurin series. $$ f(x)=e^{1-x} $$
Short Answer
Expert verified
The Maclaurin series for \( f(x) = e^{1-x} \) is \( e - ex + \frac{ex^2}{2} - \frac{ex^3}{6} + \cdots \).
Step by step solution
01
Recall the Maclaurin Series for a Known Function
The Maclaurin series for the exponential function \( e^x \) is given by: \[ e^x = \sum_{n=0}^{\infty} \frac{x^n}{n!} = 1 + x + \frac{x^2}{2!} + \frac{x^3}{3!} + \cdots \] This series will be used as a basis to derive the series for \( e^{1-x} \).
02
Substitute & Express \(f(x)\) Appropriately
We have \( f(x) = e^{1-x} = e^1 \cdot e^{-x} \). This can be seen as the product of \( e^1 \) and \( e^{-x} \). Recall that \( e^1 = e \) is a constant multiplier.
03
Derive the Maclaurin Series for \(e^{-x}\)
Replace \( x \) with \( -x \) in the Maclaurin series of \( e^x \), which gives:\[ e^{-x} = \sum_{n=0}^{\infty} \frac{(-x)^n}{n!} = 1 - x + \frac{x^2}{2!} - \frac{x^3}{3!} + \cdots \]
04
Combine Results to Write the Series for \(f(x)\)
Since \( f(x) = e \cdot e^{-x} \), and \( e \) is simply a constant multiplier, the series for \( f(x) \) will be:\[ f(x) = e \left(1 - x + \frac{x^2}{2!} - \frac{x^3}{3!} + \cdots \right) \]This expansion means that each term in the series is multiplied by \( e \).
05
Write the Final Maclaurin Series
Therefore, the Maclaurin series for \( f(x) = e^{1-x} \) is:\[ f(x) = e - ex + \frac{ex^2}{2} - \frac{ex^3}{6} + \cdots \]Each term is the corresponding term from \( e^{-x} \) multiplied by \( e \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Understanding the Exponential Function
The exponential function, typically expressed as \( e^x \), is a mathematical function showing exponential growth. Its base, \( e \), is a special constant approximately equal to 2.71828. The function has unique properties that make it an essential part of calculus and mathematical analysis.
- It's continuous and differentiable everywhere.
- The derivative and integral of \( e^x \) are itself \( e^x \).
- It is characterized by a constant rate of growth proportional to its current value.
Exploring Series Expansion
Series expansion involves representing a function as an infinite sum of terms calculated from the values of its derivatives at a single point. The Maclaurin series is one common type of series expansion.
For the exponential function \( e^x \), the series expansion starts from \( n = 0 \) and goes to infinity:
\[ e^x = \sum_{n=0}^{\infty} \frac{x^n}{n!} = 1 + x + \frac{x^2}{2!} + \frac{x^3}{3!} + \cdots\]
This series expansion allows a complex function to be expressed in simpler terms, making it easier to analyze or approximate values.
For the exponential function \( e^x \), the series expansion starts from \( n = 0 \) and goes to infinity:
\[ e^x = \sum_{n=0}^{\infty} \frac{x^n}{n!} = 1 + x + \frac{x^2}{2!} + \frac{x^3}{3!} + \cdots\]
This series expansion allows a complex function to be expressed in simpler terms, making it easier to analyze or approximate values.
- Each term is derived from the function's derivatives at zero.
- It provides a polynomial approximation for functions.
The Role of Derivation in Series
Derivation is the technique in calculus used to determine the rate at which a function is changing. With series expansion, derivation plays a critical role in forming the terms of the series.
For the Maclaurin series, each coefficient in the polynomial series is determined by the derivatives of the function evaluated at zero:
\[ f^{(n)}(0) = \text{Coefficient for } \frac{x^n}{n!}\]
For the Maclaurin series, each coefficient in the polynomial series is determined by the derivatives of the function evaluated at zero:
\[ f^{(n)}(0) = \text{Coefficient for } \frac{x^n}{n!}\]
- The first derivative gives the linear component.
- The second derivative contributes to the quadratic component.
- And so on, for higher-order derivatives.
Calculus and Its Applications
Calculus is a branch of mathematics focusing on limits, functions, derivatives, integrals, and infinite series. Its tools, such as derivation and integration, help us understand changes and find areas under curves.
- It builds upon foundational concepts like limits and functions.
- It provides ways to model dynamics and change.
- Tools from calculus are widely used in physics, engineering, economics, and beyond.