Post a New Question

math

posted by .

The 65th therm in a geometric sequence is 8000, and the 69th term is 500, find the 64th term using the geometric series sum formula

  • math -

    ar^64 = 8000
    ar^68 = 500
    divide the second by the first...
    r^4 = 1/16
    r = ± 1/2

    so if term(65) = 8000, and r = ± 1/2
    then term(64) = 8000/r = 8000/±1/2 = ± 16000

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. Math....Please help I have a deadline for tonight!

    Use the geometric sequence of numbers 1, 1/3, 1/9 , 1/27… to find the following: b) Using the formula for the sum of the first n terms of a geometric series, what is the sum of the first 10 terms?
  2. math

    he 12th term in a geometric sequence is 49 and the 14th therm is 2401, find the 15th term
  3. math

    the 65th term in a geometric sequence is 8000, and the 69th term is 500. find the 64th term
  4. Geometric Series (Algebra 2)

    I need some assistance or a formula when trying to find the first term of geometric series please! I don't understand this!!!! What is the first term of a geometric series with a summation of 289, 5 terms and a common ratio of 1/2?
  5. Math *URGENT

    Please give the answers and solutions for each. 1.If the second term is 2 and the seventh term of a geometric sequence is 64, find the 12th term. 2. Which term if the geometric sequence 18,54,162,486,... is 3,188,646?
  6. Maths

    1..The first 2 terms of a geometric progression are the same as the first two terms of an arithmetic progression.The first term is 12 and is greater than the second term.The sum of the first 3 terms od the arithmetic progression is …
  7. Math(arithmetic & Geometric Series)

    1)The sum of 6 terms of an arithmetic series is 45, the sum of 12 terms is -8. Find the first term and the common difference?
  8. Math binomial formula and sequence

    a) use the binomial formula to find the 5th term of the expansion (2x - 3)^8 ------ i got 90720x?
  9. Math

    1. Find the 11th term of the geometric sequence 64, -32, 16, -8, … . 2. Find the 1st term of a geometric sequence with a 10th term -1024 and r = -2. 3. Find the sum of each infinite geometric series, if possible. a. 10 + 2 + 2/5 …
  10. Sj

    Mathematics......Under number patterns-Geometric series If a question goes.determine the expression for the nth term of the following sequence if the a) 4th term is 24 and the 7th term is 192 in a geometric sequence.what formula do …

More Similar Questions

Post a New Question