Q. Complete the recursive formula of the arithmetic sequence−5,−25,−45,−65,….b(1)=□b(n)=b(n−1)+□
Identify First Term: Identify the first term of the sequence. The first term is given as b(1)=−5.
Determine Common Difference: Determine the common difference by subtracting the first term from the second term: −25−(−5)=−25+5=−20.
Verify Consistency: Verify the common difference by subtracting subsequent terms to ensure it is consistent: −45−(−25)=−45+25=−20 and −65−(−45)=−65+45=−20. The common difference is consistent, so it is an arithmetic sequence with a common difference of −20.
Write Recursive Formula: Write the recursive formula using the first term and the common difference. The recursive formula for an arithmetic sequence is b(n)=b(n−1)+d, where d is the common difference. Here, b(1)=−5 and d=−20.
Substitute Values: Substitute the values into the recursive formula to get the final expression: b(n)=b(n−1)−20.
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