How to use it
- Subtract consecutive terms to find d.
- Use a_n=a_1+(n−1)d.
- Check several terms.
See it in action
5,8,11,... has d=3, so a_10=5+9×3=32.
How to verify it
Starting at 5 and adding 3 nine times gives 32.
Recognize Arithmetic Sequences
An arithmetic sequence changes by a constant difference.