Q. Write an explicit formula that represents the sequence defined by the following recursive formula:a1=9 and an=31an−1Answer: an=
Given Term and Formula: We are given the first term of the sequence, a1=9, and the recursive formula an=31an−1. To find an explicit formula, we need to express an in terms of n without referencing previous terms.
Identifying Pattern: Let's look at the first few terms to identify a pattern:a1=9a2=(31)a1=(31)×9=3a3=(31)a2=(31)×3=1a4=(31)a3=(31)×1=31We can see that each term is (31) times the previous term, which is characteristic of a geometric sequence.
General Form of nth Term: The general form of the nth term for a geometric sequence is an=a1×rn−1, where a1 is the first term and r is the common ratio.In our case, a1=9 and r=31.
Substitute Values: Substitute the values of a1 and r into the formula to get the explicit formula for the sequence:an=9×(31)n−1This is the explicit formula that represents the given recursive sequence.
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