Solving Taylor's Theorem for f(x)=ln(x+1) at x=1.5

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Discussion Overview

The discussion revolves around determining the minimum number of terms required for a Taylor polynomial to approximate the function f(x) = ln(x + 1) at x = 1.5 within a specified error margin of 0.0001. The focus is on applying Taylor's theorem and understanding the behavior of the derivatives of the function.

Discussion Character

  • Mathematical reasoning
  • Homework-related
  • Technical explanation

Main Points Raised

  • One participant is attempting to compute the minimum number of terms for the Taylor polynomial but is struggling with the derivatives of ln(x + 1) and the resulting error estimation.
  • Another participant suggests that the first contributor may have overlooked the factor of 1/n! in Taylor's formula.
  • A different participant proposes using the property of alternating series, suggesting that the absolute value of the error can be approximated by the absolute value of the first omitted term.
  • The original poster clarifies that they are specifically looking for the term at which the error is less than 0.00001, expressing confusion over the number of terms needed compared to their expectations.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus, as there are differing views on the correct application of Taylor's theorem and the estimation of error. The discussion remains unresolved regarding the minimum number of terms needed.

Contextual Notes

There are indications of missing assumptions regarding the behavior of the derivatives and the specific conditions under which the error is calculated. The discussion does not fully resolve the mathematical steps involved in applying Taylor's theorem to this function.

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I'm computing the minimum number of terms for a Taylor polynomial to approximate f(1.5) within .0001 where f(x) = ln(x + 1) using Taylor's theorem, but I'm having a little trouble getting there. I keep coming up with the absolute value of the (n+1)th derivative of ln(x + 1) as (n!)/[(x+1)^(n+1)] in which case the largest value for any derivative of ln(x + 1) from 0 to x would be n! but if I use this with Taylor's Theorem I get (n!)[(1.5)^(n+1)] / (n+1)! < .0001 but this is not true for any n. Any help would be appreciated.
 
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Did you forget the 1/n! in Taylor's formula?
 
Since the series is a alternating, why not use "the absolute value of the error is less than the absolute value of the first term omitted"?
 
Well that's the problem benorin, I'm not looking for just the error, I already know what it should be. I'm looking for the term at which the error is less than .00001. In the case of the other post, even if I multiply by 1/n! I'm simply left with 1.5^(n+1) / (n+1)! which is less than .00001 only after 10 terms when it should be 9.
 

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