# Arithmetic Series help

1. Jan 3, 2007

### CathyLou

Please could someone tell me the way to find the smallest positive term of an arithmetic series (C1 level) as I cannot find a formula anywhere.

Thank you.

Cathy

2. Jan 3, 2007

### cristo

Staff Emeritus
You could rearrange the formula $$S_n=\frac{n[2a_1+(n-1)d]}{2}$$, where n is the numbers of terms, Sn is the sum of the first n terms, d is the difference between the ith and (i+1)th term, and a1 is the first term of the series.

3. Jan 3, 2007