### GCSE Maths Revision - Graphs

#### 10th April 2017

GCSE Maths Revision. Made Easy

Graphs - what are coordinates and how to draw straight line graphs using y=mx + c?

When answering questions about graphs, it is very important that you understand what coordinates are and that you know how to draw straight line graphs using the equation:

y=mx+c.

Coordinates direct you to a position on a graph relating to the origin.

The origin is where the x and y axis meet in the centre of the graph.

An example coordinate is (3, 5).

● To find the position on the graph using the coordinates we first go to the right three spaces

● Then we go up five spaces

A negative number as the first coordinate means to go left, and a negative number as the second coordinate means to go down.

A straight line graph can be written as y = mx + c.

● m is the gradient or steepness of the graph

● c is where the graph intercepts the y-axis, this is known as the y-intercept

Below are some examples of straight line graphs:

● x = 5

● y = 8

● y = x

● y = -6x

● y = 3x - 7

● x + y = 5

Some of these may not look like the equation y = mx + c but they can easily be rearranged:

● x + y = 5

● y = 5 - x

● y = -x + 5

● y = -1x + 5

From this we know that:

● The gradient is -1

● The y-intercept is 5

You must be able to understand what coordinates are and be able to draw a straight line graph using the equation y = mx + c. You will be tested on this in your exam, so get revising!

If you need any more help, check out our song which you can find in the Maths section!

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