Question

write the infinite geometric series in sigma notation. then find the sum, if it exists. show work.

the sum of an infinite geometric series is 125, and the value of r is 0.4. find the first three terms of the series.

Answer 1

the other person gave you a suitable answer to this .....

Answer 2

http://openstudy.com/study#/updates/514f2160e4b0d02faf5b2683

Answer 3

either participate in the solution process, or go someplace else please. Reposting is not considered a viable option and is considered "just wanting answers".

Answer 4

First of all I don't just want the answers but I do want more than one person to help me with the problem. if you refer back to it she wasn't 100% sure if she was right that's why she said she "thinks" she was. so for your information I just wanted more people to comment on it so that I can understand it. thank you very much. @amistre64

Answer 5

then what questions do you have about her process? it was correct for a start

Answer 6

r < 1 , so itll converge

a/(1-r) is the sum of an infinite series that converges

therefore a = 125(1-r)

Answer 7

well thank you, I just wanted to make sure the process was correct

Answer 8

@amistre64

Answer 9

only thing missing i think is the summation for it .....

Answer 10

since we are looking at an infinite sum, its going to have to involve a limit statment

Answer 11

\[S_\infty=\lim_{n\to \infty}\frac{a_1(1-r^n)}{1-r}\]
you do know how to find the first 3 terms: a1, a2, and a3 right?

Answer 12

pfft, that a correct equation, but doesnt use summation notation does it
\[\lim_{n\to \infty}\sum_{k=0}^{n}a_1~r^{k}\]

Answer 13

some texts find it ok to put the infinity sign up top of the big E, sigma

Answer 14

@amistre64 no I am not sure how to go about finding the first 3 terms

Answer 15

and it needs to be in sigma notation