Write an expression to describe the sequence below. Use n to represent the position of a term in the sequence, where n=1 for the first term.–20,–40,–60,–80,…an=_____
Q. Write an expression to describe the sequence below. Use n to represent the position of a term in the sequence, where n=1 for the first term.–20,–40,–60,–80,…an=_____
Identify type of sequence: Identify the type of sequence.The sequence is −20, −40, −60, −80, ...We notice that there is a constant difference between consecutive terms, which means the sequence is arithmetic.
Determine first term and common difference: Determine the first term (a1) and the common difference (d).The first term, a1, is −20.The common difference, d, can be found by subtracting the first term from the second term: d=−40−(−20)=−20.
Write formula for nth term: Write the formula for the nth term of an arithmetic sequence.The nth term of an arithmetic sequence is given by the formula: an=a1+(n−1)d.
Substitute values into formula: Substitute the values of a1 and d into the formula.a1=−20d=−20So, an=−20+(n−1)(−20).
Simplify expression: Simplify the expression.an=−20−20(n−1)an=−20−20n+20an=−20n
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