In a geometric series S4 = 64 and r = -2/3. The first term in the sequence is?

Thanks for your help!

1 answer

Is Sn the nth sum or the nth term?

If S4 is the 4th TERM, then
S3 = (-3/2)S4 = (-3/2)*64 = -96

S2 = (-3/2)*S3 = 144
S1 = -216

If S4 is the sum of the sequence of 4 terms, then you have to solve a more complicated equation to get S1.