Find the sum of the first 5 terms of the geometric progression 2, 6, 18, ...
Answer and explanation
Correct answer: B. 242
- Step 1: The common ratio is r = 3. Step 2. S = a(r^n - 1)/(r - 1) = 2 x (243 - 1)/2 = 242. Answer: 242. Why not the others: 486: That is the next term after the 5 terms, not their sum. 162: That is only the last term, not the sum. 240: That leaves out the first term.
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