#### Revision Notes

##### Why do we want to know about straight lines and their equations?

Straight Line Graphs (Linear Graphs) have lots of uses in mathematics – one use is in navigation.  We may want to know the equation of a straight line so we can program it into a computer that will plot the line on a screen, along with several others, to make shapes and graphics.

##### How do we find the equation of a straight line?

1. The general EQUATION of a straight line is y = mx + c where
• c  is the y-axis intercept
2. To find the EQUATION of a straight line you need TWO things:
• any point on the line
3. You might find these things from a graph, another equation or two points
4. You may be asked to give the equation in the form ax + by + c = 0
(especially if m is a fraction)
If in doubt, SKETCH IT!

## Want to aim for a Level 9?

See if you’ve got what it takes. Test yourself with our topic questions.

### Author: Simon

After 24 years teaching A Level Further Maths, Maths whizz Simon focused his attention on tutoring. He’s helped thousands of young people make sense of Maths and now he’s helping you too – aren’t you lucky! He’s even worked as an Edexcel examiner, so knows exactly what they’re looking for.