## anonymous one year ago ..

1. kanwal32

(2/3)^n-1

2. kanwal32

to infinite or 4

3. kanwal32

no i am asking till where we have to find infinite or 4

4. anonymous

@kanwal32

5. anonymous

you mean this?

6. sdfgsdfgs

yes, thats what he is asking. But do u understand the solution given in the old post? u can simply substitute 3/2 by 2/3 to get ur ans...

7. sdfgsdfgs

there is a formula given in the old post on how to calculate the sum....did u see it?

8. anonymous

I did, but it's pretty confusing, could you start me out?

9. sdfgsdfgs

u need to understand the 3 terms used in the formula: a, R and n a is the initial term in the series so in this case, it is equal to $(\frac{ 2 }{ 3})^{1-1}$ =1 ok?

10. anonymous

Okay.

11. sdfgsdfgs

R is the common ratio...so what is the ratio between the first and second term in this series? Basically what u get if u divide the second term by the first term? u already know the first term, a, is 1...

12. sdfgsdfgs

nope, first term is 1....what is the second term - when n=2....

13. sdfgsdfgs

|dw:1434612184951:dw|

14. sdfgsdfgs

no, ignore the part that I scribbled out...whatever is left, substitute n=2 and what will u get?

15. anonymous

I think it is 3

16. sdfgsdfgs

$(\frac{ 2 }{ 3 })^{(2-1)}$ = 2/3 So that is R in the formula ok?

17. sdfgsdfgs

n is simple and equal to 4 in this case. So for the formula in the last post, use the following: a=1 R=(2/3) n=4 to calculate the sum. Good luck!

18. anonymous

(2/3) (2 - 1) is 2/3. now what? @sdfgsdfgs

19. sdfgsdfgs

What is the formula to get the sum from the old post?

20. sdfgsdfgs
21. anonymous

oh okay..

22. sdfgsdfgs

a=1 R=2/3 n=4 Calculate S which is ur ans.

23. sdfgsdfgs

Put in the values we found for a, R and n....

24. anonymous

where would a go?

25. sdfgsdfgs

It IS a simple question but I think u have skipped ur study material related to the geometric series. Otherwise u should not have so much trouble :(

26. sdfgsdfgs

not funny :( sorry it is late...I need to go soon. put the values into the last line here: http://assets.openstudy.com/updates/attachments/4fb88e44e4b05565342dc675-kelly_01-1337495416339-geometric_sequence_17.gif

27. sdfgsdfgs

sorry to hear about ur health problem but u really need to understand the geometric series first before u can solve problems like this....

28. sdfgsdfgs

Correct! It is $S = \frac{ (1-(\frac{ 2 }{ 3 })^4 )}{ 1-\frac{ 2 }{ 3 } }$

29. sdfgsdfgs

We work it out this time because u found the old post. But you should read up geometric series before taking on more problems like this one.

30. anonymous

im right there and i kind of understand it a bit now..

31. sdfgsdfgs

try it again - 65/16 is not the right ans.

32. anonymous

okay one sec..

33. sdfgsdfgs

sorry i need to go now....65/27 is the right ans. good luck!