Find sum of 1 + 1/2 + 1/4 + 1/8 + ...

Find sum of 1 + 1/2 + 1/4 + 1/8 + ...

Approach: Recognize geometric series with ratio 1/2.

2. Sum = a/(1-r) = 1/(1-1/2) = 2.

Follow-up: What about 1 - 1/2 + 1/4 - 1/8 + ...?

Key concepts: geometric series, convergence, sum formula.