Sequences Tutor Help
A one-page recap of explicit and recursive formulas, plus a way to ask a tutor for a worked explanation.
1 Quick recap
The essentials on one page before you ask for help.
The two formulas
Arithmetic: an = a1 + (n−1)d ยท Geometric: an = a1 · rn−1
Explicit jumps straight to term n. Recursive (an = an−1 + d, or r · an−1) crawls from the previous term.
Stuck? Check these first
- The exponent is n − 1, not n — a1 already uses exponent 0.
- Constant difference → arithmetic. Constant ratio → geometric. Test both.
- For a far-out term, use the explicit formula — recursion is for describing, not computing.
- A recursive formula needs a1 stated, or it cannot start.
2 Ask a tutor
Tell us what you are stuck on. A tutor will follow up with a worked explanation.
3 Keep going
While you wait, review the lesson or drill practice problems.