Q. Write an explicit formula that represents the sequence defined by the following recursive formula:a1=125 and an=51an−1Answer: an=
Identify First Term & Relationship: Identify the first term and the recursive relationship.The first term of the sequence is given as a1=125. The recursive formula is given as an=51an−1, which means each term is one-fifth of the previous term.
Recognize Sequence Type: Recognize the type of sequence. Since each term is a constant fraction of the previous term, this is a geometric sequence.
Determine Common Ratio: Determine the common ratio r of the geometric sequence. The common ratio r is the factor by which we multiply one term to get the next term. From the recursive formula an=51an−1, we can see that r=51.
Write Explicit Formula: Write the explicit formula for a geometric sequence.The explicit formula for a geometric sequence is an=a1⋅r(n−1), where a1 is the first term and r is the common ratio.
Substitute Values: Substitute the values of a1 and r into the explicit formula.We have a1=125 and r=51. Substituting these values into the formula gives us $a_{n}=\(125\)\left(\frac{\(1\)}{\(5\)}\right)^{n\(-1\)}.
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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