Example

Example: Finding the Fifteenth Term of an Arithmetic Sequence

Find the fifteenth term of an arithmetic sequence where the first term is 33 and the common difference is 66.

Use the general term formula with a1=3a_1 = 3, d=6d = 6, and n=15n = 15:

an=a1+(n1)da_n = a_1 + (n - 1)d

Substitute the values:

a15=3+(151)6a_{15} = 3 + (15 - 1) \cdot 6

Simplify inside the parentheses:

a15=3+(14)6a_{15} = 3 + (14) \cdot 6

Multiply and then add:

a15=3+84=87a_{15} = 3 + 84 = 87

The fifteenth term of the sequence is 87.

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Updated 2026-05-25

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