1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Geometric Sequence and Recursive Definition

  1. May 13, 2009 #1
    1. The problem statement, all variables and given/known data

    In a Geometric Sequence find t10. t3 = 4 and t6= 4/27

    Give a recursive definition for the sequence: 1, 4, 13, 40....

    2. Relevant equations

    I know that a Geometric sequence is: tn=t1(r)n-1

    And that a recursive formula starts off with tn-1

    I'm not sure where to go from here...
  2. jcsd
  3. May 13, 2009 #2


    Staff: Mentor

    A geometric sequence has terms that look like this: {a, ar, ar2, ar3, ...}, where each term is r time the previous term. In your first problem, you have t3 = 4, so t4 = rt3 = 4r, t5 = 4t4 = ? Just work your way up to the ones you want to find.

    In your second problem, you have {1, 4, 13, 40, ...}
    The 2nd term is the first plus 3. The 3rd term is 9 plus the 2nd. The 4th term is 27 + the 3rd. Do you see a pattern?
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Geometric Sequence and Recursive Definition
  1. Recursive sequence (Replies: 3)

  2. Geometric Sequence (Replies: 7)

  3. Geometric sequence (Replies: 3)

  4. Geometric sequence (Replies: 28)

  5. Geometric Sequences (Replies: 4)