What is the sum of the first 6 terms of the geometric sequence with first term 5 and common ratio 2?
Answer and explanation
Correct answer: D. 315
- Step 1: S_n = a (r^n - 1)/(r - 1). Step 2. = 5 (64 - 1)/1 = 315. Answer: 315. Why not the others: 320: That is the (n + 1)th term, not the sum. 160: That is the nth term, not the sum. 310: That leaves out the first term.
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