Q. Find an explicit formula for the arithmetic sequence−45,−30,−15,0,…Note: the first term should be c(1).c(n)=□
Identify sequence type and pattern: Identify the type of sequence and the pattern between the terms. The sequence −45,−30,−15,0,… has a common difference between consecutive terms, indicating that it is an arithmetic sequence. The common difference can be found by subtracting any term from the subsequent term. For example, −30−(−45)=15.
Determine first term: Determine the first term of the sequence, which is given as −45. This term will be represented as c(1).
Use explicit formula: Use the explicit formula for an arithmetic sequence, which is c(n)=c(1)+(n−1)d, where c(1) is the first term and d is the common difference. We have already identified c(1) as −45 and d as 15.
Substitute values into formula: Substitute the values of c(1) and d into the formula to find the explicit formula for the sequence. The formula becomes c(n)=−45+(n−1)×15.
Simplify formula: Simplify the formula by distributing the 15 into the parentheses. This gives us c(n)=−45+15n−15.
Combine like terms: Combine like terms to get the final explicit formula for the sequence. The formula simplifies to c(n)=15n−60.
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