What is the sum of the first four terms of the geometric sequence 2, 6, 18, ...?
Answer and explanation
Correct answer: B. 80
- Step 1: The ratio is 3, so the terms are 2, 6, 18 and 54. Step 2. Their sum is . Answer: 80. Why not the others: 54 is only the fourth term, 26 is the sum of three terms, and 62 is a mistaken total.
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