Chapter 11: Problem 4
Find the Taylor polynomial \(T_{n}(x)\) for the function \(f\) at the number a. Graph \(f\) and \(T_{3}\) on the same screen. $$f(x)=x+e^{-x}, \quad a=0$$
Short Answer
Expert verified
The third-degree Taylor polynomial is \( T_3(x) = 1 + \frac{x^2}{2} - \frac{x^3}{6} \).
Step by step solution
01
Understand the Taylor Series Formula
The Taylor series of a function \( f(x) \) around a point \( a \) is given by: \[T_n(x) = f(a) + f'(a)(x-a) + \frac{f''(a)}{2!}(x-a)^2 + \ldots + \frac{f^{(n)}(a)}{n!}(x-a)^n\] For this problem, \( n = 3 \) and \( a = 0 \). So, we will find \( f(0) \), \( f'(0) \), \( f''(0) \), and \( f^{(3)}(0) \).
02
Find the First Derivative \( f'(x) \)
The function is \( f(x) = x + e^{-x} \). Differentiating with respect to \( x \), we get \[f'(x) = 1 - e^{-x}\].
03
Evaluate \( f'(0) \)
Substitute \( x = 0 \) in the first derivative: \[f'(0) = 1 - e^{0} = 1 - 1 = 0\].
04
Find the Second Derivative \( f''(x) \)
Differentiate \( f'(x) \) to get \[f''(x) = 0 + e^{-x} = e^{-x}\].
05
Evaluate \( f''(0) \)
Substitute \( x = 0 \) in the second derivative: \[f''(0) = e^{0} = 1\].
06
Find the Third Derivative \( f^{(3)}(x) \)
Differentiate \( f''(x) \) to get \[f^{(3)}(x) = -e^{-x}\].
07
Evaluate \( f^{(3)}(0) \)
Substitute \( x = 0 \) in the third derivative: \[f^{(3)}(0) = -e^{0} = -1\].
08
Assemble the Taylor Polynomial \( T_3(x) \)
Using the values found, the Taylor polynomial up to degree 3 is\[T_3(x) = f(0) + f'(0)x + \frac{f''(0)}{2!}x^2 + \frac{f^{(3)}(0)}{3!}x^3\]\[T_3(x) = (1) + (0)x + \frac{1}{2}x^2 + \frac{-1}{6}x^3 = 1 + \frac{x^2}{2} - \frac{x^3}{6}\].
09
Graph \( f(x) \) and \( T_3(x) \)
Graph the original function \( f(x) = x + e^{-x} \) and the Taylor polynomial \( T_3(x) = 1 + \frac{x^2}{2} - \frac{x^3}{6} \) on the same axes to visually inspect the approximation near \( x = 0 \).
Unlock Step-by-Step Solutions & Ace Your Exams!
-
Full Textbook Solutions
Get detailed explanations and key concepts
-
Unlimited Al creation
Al flashcards, explanations, exams and more...
-
Ads-free access
To over 500 millions flashcards
-
Money-back guarantee
We refund you if you fail your exam.
Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!
Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Taylor series
The Taylor series is a powerful mathematical tool that allows us to approximate complex functions with polynomials. It provides an infinite sum of terms calculated from the derivatives of a function evaluated at a single point. These approximations can be used to estimate the behavior of functions near that point. The formula for the Taylor series of a function \(f(x)\) around a point \(a\) is given by:
- \(T_n(x) = f(a) + f'(a)(x-a) + \frac{f''(a)}{2!}(x-a)^2 + \ldots + \frac{f^{(n)}(a)}{n!}(x-a)^n\)
differentiation
Differentiation is the fundamental process in calculus that allows us to compute a function's rate of change. By finding derivatives, we determine how a function changes at any given point.
- The first derivative of a function shows its instantaneous rate of change or slope.
- The second derivative provides information about the curvature of the graph, indicating concavity.
- The third derivative, which we'll discuss more later, can reveal changes in the rate of curvature.
exponential function
The exponential function, denoted by \(e^{-x}\), is a highly versatile tool in mathematics. It describes growth processes decaying over time, making it indispensable in various scientific and engineering contexts.
- In this problem, \(e^{-x}\) is part of the function \(f(x) = x + e^{-x}\).
- Its properties, such as having a derivative of \(-e^{-x}\), simplify our computations during differentiation.
- Understanding the behavior of exponential functions helps in visualizing how \(f(x)\) behaves.
third derivative
The third derivative of a function provides additional complexity by examining the change in the rate of a function's concavity. It can show us not just whether the function is curving, but how that rate of curvature is changing.
- For the function \(f(x) = x + e^{-x}\), the third derivative is found to be \(f^{(3)}(x) = -e^{-x}\).
- Evaluating this derivative at \(x=0\), we find \(f^{(3)}(0) = -1\).