6. Recursively Defined Sequences
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Can you find the common ratio and the first term just by looking at the explicit formula?
a_1 = 1, a_n=- 5a_(n-1)
In these formulas, r is the common ratio and a_1 is the first term. Looking at the given explicit formula, we can identify the common ratio r and the value of the first term a_1. a_n=( - 5)^(n-1) We can see that - 5 is the common ratio and the first term is 1. Now we have enough information to form a recursive formula for this sequence. la_1 = a_1 a_n = r* a_(n-1) ⇒ la_1 = 1 a_n = - 5a_(n-1)