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  • Grade 9
  • Whole terms, nth term or rule

Arithmetic and geometric sequences worksheets

A sequence follows one rule the whole way along, and once you know it you can jump straight to a term far out of reach. These free printable worksheets ask for the rule — the common difference or ratio — and for a term too far to count to.

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Ready to printArithmetic and geometric sequences
Arithmetic and geometric sequences worksheet — Whole terms, nth term or rule, free printable with answer key

The answer key prints on a separate page.

What's on this sheet

The rule is one subtraction or one division of two neighbouring terms: 5, 12, 19, 26 climbs by 7 every time, and 3, 6, 12, 24 doubles. Finding it is where every other question starts, so the common-difference and common-ratio sheets practise just that.

Why this sheet works

The nth-term sheets then ask for the 20th term, or the 8th — far enough that writing the sequence out is the long way round. That is the whole point of the formula: the first term is already there, so you add the step (n − 1) times, not n. The (n − 1) is the single most common slip, and every step-by-step walk here says it out loud.

How this one works

One question from this sheet, worked through a step at a time.

−5, −3, −1, 1, … — the 10th term

step = 2
a₁₀=−5 + 9 × 2
−5 + 18=13
the 10th term = 13
  1. This is an arithmetic sequence: it changes by 2 each step (−3 − −5 = 2).
  2. The first term is already there, so to reach the 10th term you take the step only 9 times — that is (n − 1), not n.
  3. 9 steps of 2 is 18, and −5 + 18 = 13.
  4. So the 10th term is 13.