Question

Find the sum of the geometric series with a1=343, r=-1/7, and a4=-1

Answer 1

Try this suggested option:
1. rule for the sum of this geometric series is:

`S= (a_1)/(1-r);`
2. according to the rule above:

`S= (343)/(1+ (1)/(7))= (343*7)/(8)=300.125`

answer: 300.125

P.S. note, that in this formula a₄ is not included.