Q. Write an explicit formula for an, the nth term of the sequence 27,−9,3,…Answer: an=
Identify pattern in sequence: We first identify the pattern in the sequence. The sequence starts with 27 and each term is divided by −3 to get the next term: 27,−9,3,…
Calculate ratio: This is a geometric sequence because each term is obtained by multiplying the previous term by a constant ratio. To find the ratio r, we divide the second term by the first term: r=(−9)/27=−31.
Use geometric sequence formula: The first term of the sequence, a1, is 27. The nth term of a geometric sequence is given by the formula an=a1×r(n−1), where a1 is the first term and r is the common ratio.
Substitute values into formula: Substituting the values of a1 and r into the formula, we get an=27×(−31)(n−1).
Simplify if necessary: This is the explicit formula for the nth term of the sequence. It can be simplified further if necessary, but in this case, it is already in its simplest form.
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