An infinite geometric series has common ratio -1/3 and sum 25 What is the second term of the sequence?

The equation for the sum of the infinite geometric series is S = a1/(1-r).

We know S and the ratio, so we plug in: 25 = a1/(1-(-1/3)), 25 = a1/4/3, 25 = 3a1/4, 100 = 3a1, a1 = 100/3.

 

The next term of the sequence is 100/3 times -1/3, which is -100/9