
Algebra PreAlgebra and Basic Algebra Math Forum 
 LinkBack  Thread Tools  Display Modes 
August 20th, 2008, 12:36 AM  #1 
Newbie Joined: May 2008 From: Melbourne Posts: 24 Thanks: 0  sequences and series: Arithmetic Sequences
Consider the sum of the first n integers. For what value of n will the sum first exceed 1000 ? And the formula to find the sum of n terms in an arithmetic sequence is Sn: n/2(2a+(n1)d) where a is the first term and d is the difference 
August 20th, 2008, 03:40 AM  #3 
Global Moderator Joined: Dec 2006 Posts: 19,866 Thanks: 1833 
The problem should have specified positive integers. The sequence (of positive integers ? n) in the problem then starts at 1 and has a common difference of 1, so the formula you gave, with a = d = 1, gives the sum of the integers 1, 2, . . . , n as n(n + 1)/2. Hence the integer value you have to find will be a little greater than the square root of 2000.


Tags 
arithmetic, sequences, series 
Search tags for this page 
Click on a term to search for related topics.

Thread Tools  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Dirchlet's theorem over primes in arithmetic sequences  JaimeJGG  Number Theory  7  October 1st, 2013 11:04 AM 
arithmetic sequences: why finding the nth term works  jman115  Algebra  3  December 14th, 2010 09:22 AM 
Arithmetic Sequences  brittosd  Abstract Algebra  2  April 2nd, 2009 11:56 AM 
Sequences and series help  mikeportnoy  Algebra  1  February 23rd, 2009 09:12 PM 
Help once again using Arithmetic Sequences  claudeluvstwilight  Elementary Math  1  July 11th, 2008 05:48 AM 