Find a formula for the general term an of the sequence, assuming that the pattern of the first few terms continues. (Assume that n begins with 1.)
−6, 4, − 8/ 3 , 16 /9 , − 32/ 27 , ...
Determine whether the sequence converges or diverges. If it converges, find the limit. (If an answer does not exist, enter DNE.)
an =
4(ln(n))2
/5n

Respuesta :

Answer:

The equation for the general term of the sequence is:

[tex]a_{n} = -6(-\frac{2}{3})^{n-1}[/tex]

The sequence converges to 0.

Step-by-step explanation:

First, we need to find the formula for the general term of the sequence, which is a geometric sequence, meaning that it has a common ratio, given by:

[tex]r = \frac{4}{-6} = \frac{-\frac{8}{3}}{4} = -\frac{2}{3}[/tex]

The equation of a geometric sequence has the following format:

[tex]a_{n} = a_{1}(r)^{n-1}[/tex]

In which [tex]a_{1}[/tex] is the first term.

In this question, we have that [tex]a_{1} = -6, r = -\frac{2}{3}[/tex]. So, the equation for the general term is:

[tex]a_{n} = a_{1}(r)^{n-1} = -6(-\frac{2}{3})^{n-1}[/tex]

To find if the sequence converges, we find the limit of [tex]a_{n}[/tex] as [tex]n \rightarrow \infty[/tex]. So

[tex]\lim_{n \rightarrow \infty} a_{n} = \lim_{n \rightarrow \infty} -6(-\frac{2}{3})^{n-1} = -6(-\frac{2}{3})^(\infty) = 0[/tex]

A number between 0 and 1 elevated to infinity tends to 0, so the sequence converges to zero.

The required nth term is [tex]a_n=a(-\frac{2}{3} )^n[/tex]

Geometric Series:

The Geometric series formula or the geometric sequence formula gives the sum of a finite geometric sequence.

Given that,

First Term=[tex]-6[/tex]

Common Ratio is,

[tex]\frac{4}{-6}=\frac{2}{-3} \\\frac{4}{\frac{-8}{3} }= \frac{2}{-3}[/tex]

So, the given sequence is in a geometric sequence.

So, the nth term of the given series is,

[tex]a_n=ar^{n-1}\\=-6(-\frac{2}{3} )^{n-1}\\a_n=a(-\frac{2}{3} )^n[/tex]

Learn more about the topic Geometric Series:

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