A geometric sequence has first term 5 and common ratio 3. What is the 4th term?
Answer and explanation
Correct answer: C. 135
- Step 1: a_n = a_1 q^(n-1).
- Step 2: a_4 = 5 x 3^3 = 135.
Answer
135.
Why not the others: 405 is the next term, one step too far; the other values treat the sequence as arithmetic or multiply by n.
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