We are given a recursive sequence defined by $a_1 = 2$ and $a_{n+1} = 3a_n + 4$. We want to find the general term $a_n$ of the sequence.
2025/4/24
1. Problem Description
We are given a recursive sequence defined by and . We want to find the general term of the sequence.
2. Solution Steps
We have the recursive relation . We can rewrite this as for some constant . Expanding the right side, we have . Comparing this with , we have , so and .
Therefore, . Let . Then , which means is a geometric sequence with common ratio
3. We have $b_1 = a_1 + 2 = 2 + 2 = 4$. Therefore, $b_n = b_1 \cdot 3^{n-1} = 4 \cdot 3^{n-1}$.
Since , we have .
We can check the first few terms:
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Using the recursive relation, .
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