Results 1 to 2 of 2

Math Help - Problem Geometric progression

  1. #1
    Member
    Joined
    Mar 2010
    Posts
    96

    Problem Geometric progression

    Write down the n-th therm of geometric progression if a1*a3=144 and a4-a2 = 15.

    I don't know how to solve this...
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Newbie
    Joined
    Apr 2010
    Posts
    17
    Quote Originally Posted by Nforce View Post
    Write down the n-th therm of geometric progression if a1*a3=144 and a4-a2 = 15.

    I don't know how to solve this...
    a_1 \cdot a_3 = a_1 \cdot a_1 \cdot q^2 = 144

    and

    a_4 - a_2 = a_1 \cdot q^3 + a_1 \cdot q = 15

    Now, we have a system:
    a_1 \cdot a_1\cdot q^2 = 144
    a_1 \cdot q^3 + a_1 \cdot q = 15

    Now, it is easy to solve this.

    a_1 and q determine the geometric progression.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Geometric progression problem.
    Posted in the Algebra Forum
    Replies: 1
    Last Post: October 17th 2010, 04:04 AM
  2. geometric progression word problem,
    Posted in the Pre-Calculus Forum
    Replies: 3
    Last Post: May 28th 2009, 11:38 AM
  3. Need help with this geometric progression problem
    Posted in the Pre-Calculus Forum
    Replies: 3
    Last Post: April 12th 2009, 04:17 AM
  4. Replies: 8
    Last Post: March 23rd 2009, 07:26 AM
  5. geometric progression problem
    Posted in the Algebra Forum
    Replies: 2
    Last Post: October 21st 2008, 05:07 AM

Search Tags


/mathhelpforum @mathhelpforum