Math Problem Statement

Find the sum of the series: 1 - ln(2) + (ln(2))^2 / 2! - (ln(2))^3 / 3! + (ln(2))^4 / 4! - ...

Solution

The given series is:

1ln(2)+(ln(2))22!(ln(2))33!+(ln(2))44!1 - \ln(2) + \frac{(\ln(2))^2}{2!} - \frac{(\ln(2))^3}{3!} + \frac{(\ln(2))^4}{4!} - \dots

This series resembles the Maclaurin series (Taylor series expansion around x=0x = 0) of the exponential function exe^x, which is:

ex=1+x+x22!+x33!+x44!+e^x = 1 + x + \frac{x^2}{2!} + \frac{x^3}{3!} + \frac{x^4}{4!} + \dots

Here, the signs alternate between positive and negative, suggesting it matches the series expansion of exe^{-x}, which is:

ex=1x+x22!x33!+x44!e^{-x} = 1 - x + \frac{x^2}{2!} - \frac{x^3}{3!} + \frac{x^4}{4!} - \dots

Substitution of x=ln(2)x = \ln(2):

Setting x=ln(2)x = \ln(2) into exe^{-x}, we get:

eln(2)=1eln(2)=12.e^{-\ln(2)} = \frac{1}{e^{\ln(2)}} = \frac{1}{2}.

Conclusion:

The sum of the given series is:

12\boxed{\frac{1}{2}}


Would you like further clarification on any step?

Related Questions:

  1. What is the Maclaurin series for exe^x and exe^{-x}?
  2. How do you determine the sum of an infinite geometric series?
  3. What is the role of factorials in Taylor or Maclaurin series?
  4. Why does substituting x=ln(2)x = \ln(2) simplify the exponential function?
  5. How do you verify the convergence of a series?

Tip:

Always compare a given series to known series (e.g., exponential, trigonometric, logarithmic) for quick identification and summation!

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Math Problem Analysis

Mathematical Concepts

Maclaurin Series
Exponential Function
Series Summation

Formulas

e^x = 1 + x + x^2 / 2! + x^3 / 3! + x^4 / 4! + ...
e^{-x} = 1 - x + x^2 / 2! - x^3 / 3! + x^4 / 4! - ...
e^{-ln(2)} = 1 / e^{ln(2)} = 1 / 2

Theorems

Maclaurin Series Expansion
Exponential Function Properties

Suitable Grade Level

Undergraduate (Calculus I/II)