Question

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.

5, 10, 15, 20, ...


an =

Answer 1

The given sequence is an arithmetic sequence where each term increases by 5. We can express the \( n \)-th term of the sequence using the following formula:

\[
a_n = 5n
\]

Here, \( a_n \) represents the \( n \)-th term of the sequence. When \( n = 1 \), \( a_1 = 5 \); when \( n = 2 \), \( a_2 = 10 \); when \( n = 3 \), \( a_3 = 15 \); and so on.