306 ALGEBRA •^ FORMULAS AND SEQUENCES
Formulas and sequences
A sequence is a list of numbers that follows a pattern (see pages 14-17).
By using a formula to write a rule for a sequence, we can work out the
value of any term in the sequence without having to write out the whole list.
2 4 6
In this sequence,
each term is 2 more
than the previous term
1st term 2nd term 3rd term 4th term 5th term 6th term
Number patterns
A number sequence follows a particular pattern, or rule.
Each number in a sequence is called a term. The first number
in a sequence is called the first term, the second number is
called the second term, and so on.
(^81012)
+2 +2 +2 +2 +2
The nth term
In algebra, the value of an unknown term in a sequence is
known as the nth term – the “n” stands for the unknown
value. We can write a formula called a general term of
the sequence to work out the value of any term. The unknown term is
called the nth term
...
2 4 6 8 10
1st term 2nd term 3rd term 4th term 5th term nth term
The dots show
that the sequence
goes on forever
+2 +2 +2 +2
?
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