- Arithmetic
- Found by adding a common number to the first term and then to the second term etc. Find this common
- term by subtracting a 2nd number from 1st etc. Be sure to spot the pattern.
- To find the Nth term
- – use a formula
- Where
- a_{1} = first term of sequence
- a_{n} = the term you wish to find
- d= common difference
- n – place position of the
- term IE Find term 20 – n = 20
a_{n}= a_{1} + d(n-1)
Geometric Sequences
- Found by multiplying a common number from 1 term to the next. For example multiplying 3 by the first term and then multiplying 3 by the
- first number etc. Find the common ratio by problem solving and spotting the pattern.
Can do this by dividing the 2nd term by the first term – this is called the common ratio. Can use decimals or fractions.
- To find the Nth term – use a formula
- Use exponents ( r = common ratio)
a
_{n }= a
_{1} x r
^{n-1}