Calculus

If S1 = 0.7 and S2 = 2.1 in geometric series, what would the sum of the first 12 terms in the series be?

I tried doing this, and I got 1.16 or something :S How exactly do I do this? Please tell me what formula to use. I was using the Sn = a(rn-1)/r-1

  1. 👍 0
  2. 👎 0
  3. 👁 146
  1. The geometric series up to the nth term is generally represented by the formula:
    S(n)=a + ar + ar^2 + ar^3 .... + ar^(n-1)

    Therefore
    S(1)=a=0.7
    S(2)=a+ar=a(1+r)=0.7*(1+2)
    Therefore r=2

    The formula for calculating the first n terms is
    S(n)=a(r^n-1)/(r-1)
    for n=12,
    =0.7*(2^12-1)/(2-1)
    You calculator should tell you that S(12) is below 3000.

    1. 👍 0
    2. 👎 0

Respond to this Question

First Name

Your Response

Similar Questions

  1. math

    The sum of the 1st nine terms of an arithmetic series is 216. The 1st,3rd and the 7th terms of series form the 1st three terms of a geometric series. Find the 1st term and the constant difference of the arithmetic series ?

  2. Math

    Does the following infinite geometric series diverge or converge? Explain. 3 + 9 + 27 + 81 + . . . A) It diverges; it does not have a sum. B) It converges; it has a sum.*** C) It diverges; it has a sum. D) It converges; it does

  3. Math

    Does the following infinite geometric series diverge or converge? Explain. 1/7+1/28+1/112+1/448 A) It converges; it has a sum.*** B) It diverges; it does not have a sum. C) It diverges; it has a sum. D) It converges; it does not

  4. math B30

    If the seventh term of a geometric series is 192, and the first term is 3, find the sum of the first 8 terms of the series

  1. Algebra 2

    Describe an infinite geometric series with a beginning value of 2 that converges to 10. What are the first four terms of the sequence? a{1} = first term of series ∞ Infinite Sum = ∑ a{1} • r^(n – 1) = a{1} ⁄ (1 – r)

  2. sum geometric series

    what is the sum of geometric infinite series 3/2+ 9/16+ 27/128+ 81/1024=.... i know the formula is S=a/(1-r) my teacher, he usually transforms into a formula of the sum series and finds out a and r.but i don't how to do that. the

  3. Algebra 2

    How would I find the sum of the geometric series given? 1/5 - 1/25 + 1/125

  4. Algebra 2

    What is the sum of the geometric series 10 E 6(2)^n n=1 I'm a little lost as to what I should do here. Could someone please clarify how this one is done?

  1. math

    in a geometric series t1=23,t3=92 and the sum of all of the terms of the series is 62 813. how many terms are in the series?

  2. Math

    Does the following infinite geometric series diverge or converge? Explain. 1/5 + 1/25 + 1/125 + 1/625 A) It diverges; it has a sum. B) It converges; it has a sum. C) It diverges; it does not have a sum. D) It converges; it does

  3. Math

    If S1 = 0.7 and S2 = 2.1 in a geometric series, determine the sum of the first 12 terms in the series. Be sure to show all of your work.

  4. Calculus

    Consider the series 1/4+1/6+1/9+2/27+4/81+.... Does the series converge or diverge? Is the series arithmetic, geometric, neither, or geometric with an absolute value of the common ration being greater/ less than 1?

You can view more similar questions or ask a new question.