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

a_(1)=125" 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=125 and an=15an1 a_{1}=125 \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=125 and an=15an1 a_{1}=125 \text { and } a_{n}=\frac{1}{5} a_{n-1} \newlineAnswer: an= a_{n}=
  1. Identify First Term & Relationship: Identify the first term and the recursive relationship.\newlineThe first term of the sequence is given as a1=125a_{1}=125. The recursive formula is given as an=15an1a_{n}=\frac{1}{5}a_{n-1}, which means each term is one-fifth of the previous term.
  2. Recognize Sequence Type: Recognize the type of sequence. Since each term is a constant fraction of the previous term, this is a geometric sequence.
  3. Determine Common Ratio: Determine the common ratio rr of the geometric sequence. The common ratio rr is the factor by which we multiply one term to get the next term. From the recursive formula an=15an1a_{n}=\frac{1}{5}a_{n-1}, we can see that r=15r=\frac{1}{5}.
  4. Write Explicit Formula: Write the explicit formula for a geometric sequence.\newlineThe explicit formula for a geometric sequence is an=a1r(n1)a_{n}=a_{1}\cdot r^{(n-1)}, where a1a_{1} is the first term and rr is the common ratio.
  5. Substitute Values: Substitute the values of a1a_{1} and rr into the explicit formula.\newlineWe have a1=125a_{1}=125 and r=15r=\frac{1}{5}. Substituting these values into the formula gives us $a_{n}=\(125\)\left(\frac{\(1\)}{\(5\)}\right)^{n\(-1\)}.
  6. Simplify Expression: Simplify the expression if possible.\(\newline\)The expression \(a_{n}=125\times\left(\frac{1}{5}\right)^{n-1}\) is already in its simplest form, so no further simplification is needed.

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