The problem asks us to analyze the sequence $a_n = e^{-n} \sin n$. We need to find the first few terms of the sequence, determine if it converges or diverges, and if it converges, find the limit as $n$ approaches infinity.

AnalysisSequencesLimitsConvergenceSqueeze TheoremTrigonometric FunctionsExponential Functions
2025/5/27

1. Problem Description

The problem asks us to analyze the sequence an=ensinna_n = e^{-n} \sin n. We need to find the first few terms of the sequence, determine if it converges or diverges, and if it converges, find the limit as nn approaches infinity.

2. Solution Steps

First, let's find the first few terms of the sequence:
a1=e1sin10.3096a_1 = e^{-1} \sin 1 \approx 0.3096
a2=e2sin20.1231a_2 = e^{-2} \sin 2 \approx 0.1231
a3=e3sin30.0142a_3 = e^{-3} \sin 3 \approx 0.0142
a4=e4sin40.0149a_4 = e^{-4} \sin 4 \approx -0.0149
a5=e5sin50.0128a_5 = e^{-5} \sin 5 \approx -0.0128
a6=e6sin60.0009a_6 = e^{-6} \sin 6 \approx -0.0009
Now, let's analyze the convergence of the sequence. We have an=ensinna_n = e^{-n} \sin n. We can rewrite this as an=sinnena_n = \frac{\sin n}{e^n}. We know that 1sinn1-1 \le \sin n \le 1 for all nn. Therefore, we have:
1ensinnen1en-\frac{1}{e^n} \le \frac{\sin n}{e^n} \le \frac{1}{e^n}.
As nn approaches infinity, ene^n also approaches infinity. Therefore, limn1en=0\lim_{n \to \infty} \frac{1}{e^n} = 0 and limn1en=0\lim_{n \to \infty} -\frac{1}{e^n} = 0.
By the squeeze theorem, since 1ensinnen1en-\frac{1}{e^n} \le \frac{\sin n}{e^n} \le \frac{1}{e^n} and limn1en=0\lim_{n \to \infty} -\frac{1}{e^n} = 0 and limn1en=0\lim_{n \to \infty} \frac{1}{e^n} = 0, we have:
limnsinnen=0\lim_{n \to \infty} \frac{\sin n}{e^n} = 0.
Therefore, the sequence an=ensinna_n = e^{-n} \sin n converges to
0.

3. Final Answer

The first few terms are approximately: 0.3096, 0.1231, 0.0142, -0.0149, -0.0128, -0.
0
0
0

9. The sequence converges.

The limit of the sequence is
0.

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