How do you find the sum of the infinite geometric series 3-1+1/3...?

1 Answer
Anthony X
Apr 28, 2016

From 3 to -1 to 1/3, what would the common ratio be?

Well, it seems as if we are multiplying by -1/3 because from 3 to -1 would be 3*-1/3 and from -1 to 1/3 would be -1*-1/3

From here, we can just apply the infinite series formula, 1/(1-r) because the r is between -1 and 1.

Thus, the sum is 1/(1-(-1/3)) or 1/(1+1/3) or 1/(4/3)

or 3/4

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