# How do you find the formula for a_n for the arithmetic sequence a_1=15, d=4?

May 24, 2017

Look at the first few terms and discover a pattern.

#### Explanation:

Look at the first few terms:

${a}_{1} = 15 = 15 + 4 \left(0\right)$

${a}_{2} = 19 = 15 + 4 \left(1\right)$

${a}_{3} = 23 = 15 + 4 \left(2\right)$

${a}_{n} = {a}_{1} + d \left(n - 1\right)$