Series expansion for ln(1+x)

Series Expansion for ln(1+x)

Understanding the Series Expansion for ln(1+x)

  • The natural logarithm function, often represented as ln(x), is the inverse of the exponential function.
  • The series expansion for ln(1+x) allows us to express it as an infinite series.
  • The series expansion for ln(1+x) for x < 1 is given by: ln(1+x) = x - x²/2 + x³/3 - x⁴/4 + x⁵/5 - x⁶/6 + …

Properties of the Series Expansion

  • Note that the series alternate in signs between positive and negative, starting with a positive sign.
  • The coefficients are the reciprocals of the natural numbers. They are placed in increasing order starting from 1.
  • The powers of x also start from 1 and increase by 1 in each term.

Utilising the Series Expansion

  • By using the first few terms of the series expansion, we can approximate the value of ln(1+x) for x < 1.
  • The more terms we use, the more accurate our approximation will be.
  • Be cautious when using this series expansion for values of x outside the interval -1 < x < 1 as it may not converge.

Tips on Series Expansion for ln(1+x)

  • Familiarity with the form and pattern of the series expansion is key in efficiently making use of it.
  • Practice rewriting the series expressions from memory to solidify understanding.
  • Apply the series in variety of problem-solving contexts to enhance the practical understanding.
  • Pay attention to the alternating signs and the increasing power of x in each term.
  • Be careful about the region of convergence while using the expansion to avoid mistakes.
  • Always perform a reality check on your answers, especially when doing approximations. If your answer seems unreasonable, review your work for errors.