Math Problem Statement

For the series below calculate, find the number of terms n that must be added in order to find the sum to the indicated accuracy: ∑ (-1)^n * n^5 / n^0.6, where |error| < 0.01.

Solution

To solve this, the series provided is alternating, and the problem requires determining the number of terms nn needed to ensure that the error is less than 0.010.01.

For an alternating series, the error can be approximated by the magnitude of the next term: Erroran+1<0.01\text{Error} \approx \left| a_{n+1} \right| < 0.01

The general term of the series is: an=(1)n(n5)n0.6a_n = \frac{(-1)^n (n^5)}{n^{0.6}}

Simplified (ignoring the alternating factor): an=n5n0.6=n50.6=n4.4a_n = \frac{n^5}{n^{0.6}} = n^{5 - 0.6} = n^{4.4}

Steps:

  1. Set an+1<0.01|a_{n+1}| < 0.01: (n+1)5(n+1)0.6<0.01    (n+1)4.4<0.01\frac{(n+1)^5}{(n+1)^{0.6}} < 0.01 \implies (n+1)^{4.4} < 0.01

  2. Solve for n+1n+1 by taking logarithms: n+1<(0.01)14.4n+1 < \left(0.01\right)^{\frac{1}{4.4}}

  3. Compute n+1n+1 and round up to the nearest integer.

Let me calculate this for you.import math

Solve for n+1 using the formula: n+1 < (0.01)^(1/4.4)

error_threshold = 0.01 exponent = 4.4

n_plus_1 = (error_threshold) ** (1 / exponent)

Find n by subtracting 1 and taking the ceiling for accuracy

n = math.ceil(n_plus_1 - 1) n00successThe calculated nn is 00, meaning the series converges quickly, and even the first term would provide sufficient accuracy to meet the error threshold of 0.010.01.

Would you like to see the detailed steps or have further clarifications? Here are some related questions to deepen your understanding:

  1. How does the alternating series error estimation method work?
  2. What would happen if the error threshold were reduced further?
  3. Can we generalize this approach to other series?
  4. How does the behavior of n4.4n^{4.4} affect the series convergence?
  5. How does rounding up influence the practical result?

Tip: For alternating series, focusing on the magnitude of the next term is a quick way to estimate the error.

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Math Problem Analysis

Mathematical Concepts

Alternating Series
Error Estimation
Series Convergence
Exponential and Logarithmic Functions

Formulas

Error ≈ |a_(n+1)| < threshold
a_n = (-1)^n * n^5 / n^0.6
n^(4.4)

Theorems

Alternating Series Remainder Theorem

Suitable Grade Level

Undergraduate Mathematics