Math Problem Statement

Converge or diverge absolutely?

Converge or diverge absolutely?

Solution

The series given is:

n=1nnn!.\sum_{n=1}^\infty \frac{n^n}{n!}.

To determine whether the series converges or diverges, let us analyze the terms using standard convergence tests.

Step 1: Examine the general term

The general term of the series is: an=nnn!.a_n = \frac{n^n}{n!}.

Step 2: Apply the ratio test

The ratio test involves finding: L=limnan+1an.L = \lim_{n \to \infty} \left| \frac{a_{n+1}}{a_n} \right|. Substitute an=nnn!a_n = \frac{n^n}{n!}: an+1an=(n+1)n+1(n+1)!nnn!=(n+1)n+1n!nn(n+1)!.\frac{a_{n+1}}{a_n} = \frac{\frac{(n+1)^{n+1}}{(n+1)!}}{\frac{n^n}{n!}} = \frac{(n+1)^{n+1} \cdot n!}{n^n \cdot (n+1)!}. Simplify: an+1an=(n+1)n+1nn(n+1)=(n+1)n(n+1)nn(n+1)=(n+1)nnn.\frac{a_{n+1}}{a_n} = \frac{(n+1)^{n+1}}{n^n \cdot (n+1)} = \frac{(n+1)^n \cdot (n+1)}{n^n \cdot (n+1)} = \frac{(n+1)^n}{n^n}. Simplify further: [ \frac{a_{n+1}}{a_n} = \left(\frac{n+1}{

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Math Problem Analysis

Mathematical Concepts

Infinite Series
Convergence Tests
Ratio Test

Formulas

a_n = n^n / n!
L = lim (n → ∞) |a_(n+1) / a_n|

Theorems

Ratio Test

Suitable Grade Level

Undergraduate Level (Calculus II or Higher)