
Algebra PreAlgebra and Basic Algebra Math Forum 
 LinkBack  Thread Tools  Display Modes 
April 13th, 2012, 05:12 AM  #1 
Member Joined: Apr 2012 Posts: 90 Thanks: 0  Geometric Progression
Hello World, I am urgently looking for solutions to these questions. Would appreciate the help! 10 15 1.)Prove that a.) ? 8(0.5)^n and b.) ? 2(5^(n)) is geometric and find each sum. n=1 n=1 How do you prove that it is geometric and I think I know how to find each sum, if proving that the series is geometric gives me the common ratio. 2.) Nine numbers are in GP and are alternately positive and negative. If the first number is 24 and the last number is 3/32, find the sum of the numbers. I got U1 = 24 and ar^8 = 3/32 Therefore, r^8 = (3/32)/(24) and I got 1/256 Since it is alternately positive and negative, I believe the common ratio should be a negative. But then how do I continue, or am I even doing it right? 100 3.) Evaluate ? (0.01n+0.09^n) Thank you much! n=1 
April 13th, 2012, 05:48 AM  #2 
Senior Member Joined: Jul 2011 Posts: 227 Thanks: 0  Re: Geometric Progression
1. Use the definition of a geometric serie. 2. What you have done so far is correct, note that , but indeed because you have an alternating sequence From this point, you should be able to find the sum of the numbers. 3. Note that you have a sum that means you can split the summation as: The first summation is an arithmetic serie and the second is a geometric serie. 
April 13th, 2012, 06:34 AM  #3  
Math Team Joined: Dec 2006 From: Lexington, MA Posts: 3,267 Thanks: 407  Re: Geometric Progression Hello, Ter! Quote: Quote:  

Tags 
geometric, progression 
Thread Tools  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Geometric progression.  jiasyuen  Algebra  7  March 23rd, 2014 09:29 PM 
Geometric progression  jiasyuen  Algebra  1  November 19th, 2013 03:13 AM 
Geometric Progression need help  naman  Algebra  1  March 5th, 2013 07:26 AM 
geometric progression  islam  Number Theory  3  July 20th, 2011 07:39 AM 
Geometric Progression  KingATG  Algebra  2  August 8th, 2010 02:25 PM 