Q. Find an explicit formula for the geometric sequence3,15,75,375,….. Note: the first term should be a (1).a(n)=
Identify sequence type: Identify the type of sequence.The sequence 3,15,75,375,extellipsis is a geometric sequence because each term is obtained by multiplying the previous term by a constant ratio r.
Determine first term: Determine the first term (a1) of the sequence.The first term of the sequence is 3.
Calculate common ratio: Calculate the common ratio (
) of the sequence.To find the common ratio, divide the second term by the first term: r=315=5.
Write explicit formula: Write the explicit formula for the nth term of the geometric sequence.The explicit formula for a geometric sequence is an=a1⋅r(n−1). Substitute a1=3 and r=5 into the formula to get an=3⋅5(n−1).
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