Q. Write an explicit formula that represents the sequence defined by the following recursive formula:a1=5 and an=−3an−1Answer: an=
Identify Terms: To find the explicit formula, we start by looking at the first few terms of the sequence using the recursive formula. a1=5 (given)a2=−3a1=−3(5)=−15a3=−3a2=−3(−15)=45a4=−3a3=−3(45)=−135
Recognize Pattern: We notice a pattern where each term is −3 times the previous term. This is a geometric sequence with the first term a1=5 and a common ratio r=−3. The explicit formula for a geometric sequence is given by: an=a1×r(n−1)
Apply Explicit Formula: Substitute the values of a1=5 and r=−3 into the formula to get the explicit formula for this sequence:an=5⋅(−3)n−1
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