Question

Given the nth term for this arithmetic sequence, how to find the common difference and the first four terms too? `a_n` = 3n - 2

Answer 1

The first four terms are
`a_1=1`
`a_2=4`
`a_3=7`
`a_4=10`

Common difference is
`d=3`

Explanation:

`a_n=3n-2`
`n=1`

`a_1=3x1-2=3-2=1`
`n=2`
`a_2=3x2-2=6-2=4`
`n=3`
`a_3=3x3-2=9-2=7`
`n=4`
`a_4=3x4-2=12-2=10`

The first four terms are
`a_1=1`
`a_2=4`
`a_3=7`
`a_4=10`
Common difference is
`a_2-a_1=4-1=3`
`a_3-a_2=7-4=3`
`a_4-a_3=10-7=3`

`d=3`