
Number Theory Number Theory Math Forum 
 LinkBack  Thread Tools  Display Modes 
January 14th, 2013, 04:00 AM  #1 
Member Joined: Jan 2013 Posts: 93 Thanks: 0  sum of the first 50 terms
Determine the sum of the first 50 terms in the series 1+(1/2)+(1/2)^2 +(1/2)^3 +..... I actually already answered this question but would like to get confirmation on it! I used formula: Sn=(a1+an)/2 n After futher calculations: an=a1+(n1) r , r=1/2, a50=? a50= 51/2 And then using main formula S50= 1325/2=662.5 Am i correct? 
January 14th, 2013, 05:06 AM  #2 
Global Moderator Joined: Nov 2006 From: UTC 5 Posts: 16,046 Thanks: 938 Math Focus: Number theory, computational mathematics, combinatorics, FOM, symbolic logic, TCS, algorithms  Re: sum of the first 50 terms
The sum should be bounded above by 2, right?

January 14th, 2013, 05:17 AM  #3 
Member Joined: Jan 2013 Posts: 93 Thanks: 0  Re: sum of the first 50 terms
Yes, but i thought i already did that. S50= ((1+25.5)/ 2)* 50= 53/2 *25= 1325/2= 662.5 
January 14th, 2013, 05:59 AM  #4  
Math Team Joined: Dec 2006 From: Lexington, MA Posts: 3,267 Thanks: 408  Re: sum of the first 50 terms Hello, Agata78! Quote: [color=beige]n . . . . .[/color]  
January 14th, 2013, 06:12 AM  #5  
Global Moderator Joined: Nov 2006 From: UTC 5 Posts: 16,046 Thanks: 938 Math Focus: Number theory, computational mathematics, combinatorics, FOM, symbolic logic, TCS, algorithms  Re: sum of the first 50 terms Quote:
 
January 14th, 2013, 06:15 AM  #6 
Member Joined: Jan 2013 Posts: 93 Thanks: 0  Re: sum of the first 50 terms
I have completely different formula. But i think yours makes more sense then mine! Thank you 

Tags 
sum, terms 
Thread Tools  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Find the sum of the first 50 terms  stevecowall  Algebra  8  February 28th, 2012 12:59 PM 
Finding sum of the terms  stevecowall  Algebra  1  February 17th, 2012 06:53 PM 
It is possible to rearrange n = ln(x)/ln(y) in terms of x/y?  jazzycafe  Algebra  6  November 18th, 2009 05:58 PM 
terms of a over b  riponks  Elementary Math  5  September 24th, 2009 03:50 AM 
terms  Soha  Algebra  4  December 19th, 2006 04:23 PM 