Q. Write an explicit formula for an, the nth term of the sequence 7,15,23,…Answer: an=
Identify Sequence Type: Identify whether the given sequence is geometric or arithmetic. The sequence 7,15,23,… has a common difference between consecutive terms, so it is an arithmetic sequence.
Find First Term and Difference: Determine the first term (a1) and the common difference (d) of the sequence. The first term a1 is 7. To find the common difference, subtract the first term from the second term: d=15−7=8.
Use Explicit Formula: Use the explicit formula for an arithmetic sequence, an=a1+(n−1)d, where a1 is the first term and d is the common difference. For the sequence 7,15,23,…, a1 is 7 and d is 8.
Substitute Values: Substitute the values of a1 and d into the formula to write an expression to describe the sequence. The expression for the sequence 7,15,23,… is an=7+(n−1)×8.
Simplify Expression: Simplify the expression to find the explicit formula for the nth term. an=7+8n−8, which simplifies to an=8n−1.
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