Find the nth term from the common difference, and use it to test values and find positions.
What you will learn
- Find the nth term of a linear sequence
- Decide whether a number is in a sequence
- Find which term has a given value
Difference, then adjust
- 5, 8, 11, 14, ...
- the difference is 3, so start with 3n: 3, 6, 9, 12
- each term is 2 more than 3n
- nth term = 3n + 2
Check with n = 1: 3 + 2 = 5. A decreasing sequence has a negative difference: 20, 17, 14, ... is −3n + 23.
The rest of this lesson and its 7 practice questions are locked.
In this lesson
- Difference, then adjust
- Is it in the sequence?
- The nth term from two terms
- Try it: Watch the sequence on a graph
7 practice questions, marked as you go; about 25 minutes in all.
In this unit: Sequences
Term-to-term rules, the nth term of linear sequences, special sequences, geometric sequences and (Higher) the nth term of quadratic sequences.
- Term-to-term rules
- The nth term of a linear sequence
- Special sequences
- Geometric sequences
- Quadratic sequences