Q. Find an explicit formula for the geometric sequence −1,−7,−49,−343 the first term should be b(1)
Identify Sequence Type: Identify the type of sequence.The sequence −1, −7, −49, −343, ... appears to be geometric because each term is obtained by multiplying the previous term by a common ratio.
Find First Term and Ratio: Determine the first term b(1) and the common ratio r of the sequence.First term: b(1)=−1To find the common ratio, divide the second term by the first term: r=−1−7=7
Formulate Explicit Formula: Formulate the explicit formula for the geometric sequence using b(1) and r. The general formula for the nth term of a geometric sequence is b(n)=b(1)⋅r(n−1). Substitute −1 for b(1) and 7 for r to get the explicit formula. b(n)=−1⋅7(n−1)
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