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Explain why the sequence with terms ( aₙ=sin (nπ/n+1)) is convergent.

User Rednafi
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2 Answers

5 votes

Final Answer:

The sequence
\(a_n = \sin\left((n\pi)/(n+1)\right)\) is convergent.

Step-by-step explanation:

This sequence can be rewritten as
\(a_n = \sin\left((\pi)/(1+(1)/(n))\right)\) . As
\(n\) approaches infinity,
\((1)/(n)\) tends towards zero, making the argument of the sine function approach
\(\pi\) . For
\(n\) , larger values lead to
\((1)/(n)\) being negligibly small, resulting in the argument of the sine function being extremely close to
\(\pi\) . The sine of an angle close to
\(\pi\) is zero. Therefore, as
\(n\) tends towards infinity,
\(a_n\) tends towards
\(\sin(\pi) = 0\) .

This can be proven by considering the limit as
\(n\) approaches infinity for
\(a_n\) . Taking the limit of
\(a_n\) as
\(n\) approaches infinity:


\[\lim_{{n \to \infty}} \sin\left((n\pi)/(n+1)\right) = \sin(\pi) = 0\]

Using the fact that the sine function is continuous, we can directly substitute the limiting value of the argument,
\(\pi\) , to obtain the result
\(0\) . Therefore, the sequence
\(a_n\) converges to
\(0\) as
\(n\)approaches infinity.

User Fabio Manzano
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8.5k points
4 votes

Main Answer:

The sequence converges because the sine function, bounded between -1 and 1, approaches a fixed value as n tends to infinity.

Step-by-step explanation:

The given sequence (aₙ = sin(nπ/n+1)) is convergent due to the nature of the sine function and the specific form of the sequence. The sine function is bounded between -1 and 1 for any real input, and in this sequence, the argument of the sine function is nπ/(n+1). As n approaches infinity, the term n/(n+1) approaches 1, and consequently, the argument of the sine function approaches nπ. Since the sine function oscillates periodically with a period of 2π, the sequence becomes periodic with each term converging to a specific value within the interval [-1, 1].

This behavior ensures the convergence of the sequence as n tends to infinity. The boundedness of the sine function and the specific structure of the sequence lead to a convergence pattern that is consistent and predictable, providing a mathematical basis for the convergence of the given sequence. In essence, the convergence is a result of the interplay between the periodicity of the sine function and the characteristics of the sequence's form.

User Erik Shilts
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8.3k points