In order to work with sequences and
series, there are formulae that you should memorise. Do you know them? When you
think you know, move the mouse over the question mark to check.

Here are some examples of arithmetic series:

0, 2, 4, 6, 8, 10, 12, ...

13, 10, 7, 4, 1, -2, -5, ...

0.7, 1.4, 2.1, 2.8, 3.5, 4.2, ...

In general an arithmetic series has first term

Here are some examples of arithmetic series:

0, 2, 4, 6, 8, 10, 12, ...

13, 10, 7, 4, 1, -2, -5, ...

0.7, 1.4, 2.1, 2.8, 3.5, 4.2, ...

In general an arithmetic series has first term

*a*and common difference*d*.## Software/Applets used on this page

## Glossary

### series

the sum of terms in a sequence

### union

The union of two sets A and B is the set containing all the elements of A and B.

### work

Equal to F x s, where F is the force in Newtons and s is the distance travelled and is measured in Joules.