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Write an explicit formula that represents the sequence defined by the following recursive formula:

a_(1)=75" and "a_(n)=(1)/(5)a_(n-1)
Answer: 
a_(n)=

Write an explicit formula that represents the sequence defined by the following recursive formula:\newlinea1=75 and an=15an1 a_{1}=75 \text { and } a_{n}=\frac{1}{5} a_{n-1} \newlineAnswer: an= a_{n}=

Full solution

Q. Write an explicit formula that represents the sequence defined by the following recursive formula:\newlinea1=75 and an=15an1 a_{1}=75 \text { and } a_{n}=\frac{1}{5} a_{n-1} \newlineAnswer: an= a_{n}=
  1. Identify Pattern: The recursive formula given is an=15an1a_n = \frac{1}{5}a_{n-1}, with the initial condition a1=75a_{1} = 75. To find an explicit formula, we need to express ana_n in terms of nn without referencing previous terms.
  2. Calculate Terms: Let's look at the first few terms to identify a pattern. We start with a1=75a_{1} = 75. Using the recursive formula, a2=15a1=15×75a_{2} = \frac{1}{5}a_{1} = \frac{1}{5} \times 75. Then, a3=15a2=15×15×75a_{3} = \frac{1}{5}a_{2} = \frac{1}{5} \times \frac{1}{5} \times 75, and so on.
  3. Derive Explicit Formula: We can see that each term is (1/5)(1/5) times the previous term. So, ana_{n} can be written as a1×(1/5)n1a_{1} \times (1/5)^{n-1}, because each step we multiply by (1/5)(1/5) one more time than the previous step.
  4. Substitute Initial Condition: Substituting the initial condition a1=75a_{1} = 75 into the pattern we found, the explicit formula becomes an=75×(15)n1.a_{n} = 75 \times \left(\frac{1}{5}\right)^{n-1}.

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