s=a1/1-r

help!

this is the formula for a converging infinite series. a1 is the first term and r is the common ratio

sa11r help this is the formula for a converging infinite series a1 is the first term and r is the common ratio class=

Respuesta :

Answer:

4

Step-by-step explanation:

This is an infinite geometric series. This has a sum of  [tex]\frac{a}{1-r}[/tex]

Where

a is the first term, and

r is the common ratio (one term divided by the previous term)

Let's figure out the first 2 terms by plugging in n = 1 first and then n = 2 for the series.

First term:

[tex]3(\frac{1}{4})^{n-1}\\=3(\frac{1}{4})^{1-1}\\=3(\frac{1}{4})^0\\=3(1)\\=3[/tex]

Second term:

[tex]3(\frac{1}{4})^{n-1}\\=3(\frac{1}{4})^{2-1}\\=3(\frac{1}{4})^1\\=3(\frac{1}{4})\\=\frac{3}{4}[/tex]

Let's see the common ratio:  [tex]\frac{\frac{3}{4}}{3}\\=\frac{3}{4}*\frac{1}{3}\\=\frac{1}{4}[/tex]

Thus we have a = 3 and r = 1/4. Plugging into the formula of the infinite sum, we get:

[tex]s=\frac{a}{1-4}=\frac{3}{1-\frac{1}{4}}=\frac{3}{\frac{3}{4}}=3*\frac{4}{3}=4[/tex]

So, the answer is 4