If the sum of an infinite geometric series is 12 and the common ratio is , what is the first term ?
Answer and explanation
Correct answer: B.
- Step 1: Use the sum formula for a convergent infinite geometric series: , where .
- Step 2: Substitute and : . Multiply both sides by : .
Answer
.
Why not the others: is (multiplying by the common ratio instead of ); results from using ; is .
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