Question

How would i find the explicit formula for the arithmetic sequence -11,-3,5,12

Answer 1

Arithmetic Sequence Formula:

$a_n=a_1+(n-1)d$

We have:

$a_1=-11,\ a_2=-3,\ a_3=5,\ a_4=12,\ ...$

$d=a_{n+1}-a_n\to d=-3-(-11)=-3+11=8$

Substitute:

$a_n=-11+(n-1)(8)=-11+8n-8=8n-19$

Answer: $a_n=8n-19$