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:
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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