Progressions and finding the sum of terms

**fcabanski** · September 24th 2009, 08:45 AM

Given this series (2,4,6,8,10,12...) the formula to find the sum of all numbers up to an nth term in the series is n(n+1).

For example, the sum of numbers up to and including the 2nd term is 2(2+1)=6.

But for this series (3,6,9,12,15...) what is the formula to find the sum of all numbers up to the nth term in the series.

What type of progression is it?

How is the formula found?

**red_dog** · September 24th 2009, 09:03 AM

Is an arithmetic progression.

$a_1=3, \ a_n=3n$

The sum is $S_n=\frac{(a_1+a_n)n}{2}=\frac{3n(n+1)}{2}$

**fcabanski** · September 24th 2009, 09:53 AM

Thanks for the help.

Thread: Progressions and finding the sum of terms

LinkBack

Thread Tools

Display

Progressions and finding the sum of terms

Similar Math Help Forum Discussions

[SOLVED] Even more arithmetic progressions. in terms of d...

finding logs in terms of another log

Finding the next four terms of this sequence?

Recursion and finding terms

Finding the next terms in series

Search Tags