Math Problem Statement

Which of the following is the power series representation centered at x = 2 for the function: 1 / (1 + 5x)?

Solution

To find the power series representation of the function 11+5x\frac{1}{1 + 5x} centered at x=2x = 2, we can follow these steps:

  1. Rewrite the Function for Series Expansion: A standard power series expansion around x=0x = 0 for 11u\frac{1}{1 - u} is given by: 11u=n=0un,for u<1.\frac{1}{1 - u} = \sum_{n=0}^{\infty} u^n, \quad \text{for } |u| < 1.

  2. Express in Terms of a New Variable: We want a series centered at x=2x = 2. Define a new variable uu such that: u=5(x2).u = -5(x - 2). Then: 1+5x=1(5(x2))=1u.1 + 5x = 1 - (-5(x - 2)) = 1 - u. Now our function becomes: 11+5x=11u=n=0(5(x2))n.\frac{1}{1 + 5x} = \frac{1}{1 - u} = \sum_{n=0}^{\infty} (-5(x - 2))^n.

  3. Expand the Series: Substituting u=5(x2)u = -5(x - 2), we get: n=0(5)n(x2)n.\sum_{n=0}^{\infty} (-5)^n (x - 2)^n.

So, the power series representation centered at x=2x = 2 for 11+5x\frac{1}{1 + 5x} is: n=0(5)n(x2)n.\sum_{n=0}^{\infty} (-5)^n (x - 2)^n.

Would you like further clarification on any steps?

Related Questions

  1. How do you find the radius of convergence for this power series?
  2. How does the power series change if the center is at a different point?
  3. How can the ratio test be applied to confirm convergence of this series?
  4. What is the general formula for a Taylor series expansion of a function around a point?
  5. How does the presence of 5x5x affect the convergence properties of this series?

Tip

Remember, a power series is valid within the interval where the series converges; finding this interval is key for accurate results.

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Math Problem Analysis

Mathematical Concepts

Power Series
Series Expansion
Function Centering

Formulas

Power series for 1 / (1 - u) is ∑ u^n for |u| < 1
Rewriting: u = -5(x - 2)

Theorems

Taylor Series

Suitable Grade Level

Grades 11-12