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# Why is using a table of values useful?

By Lee Mansfield on the 11th of June, 2012

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It gives you a quick list of the points to plot when having to draw a line (or even a curve). Plotting these points on your x-y graph will then tell you what your line (or curve) looks like.

By Jim Gather on the 11th of June, 2012

## Draw lines such as y = 2x + 3 using a table of values

Linear equations are always straight lines when you draw them, hence the word LINEar.

You can spot them because they only have an x term in them, and not x to the power of anything. So, x2 will not give you a linear eqation

Since linear equations are straight lines, they are very simple to do when you have to sketch a graph when working through worksheets or in your exam.

You need to know at least two sets of values (two points on the graph), then you just join them up with a ruler.

But to be more accurate, it is best to create a table of values with more than 2 points to draw the line.

This table will then tell you the x and y coordinates you need to plot, and then you just join them up with a ruler.

For example,

y = 2x + 4

Let's choose x = -2, -1, 0, 1, 2

x = -2
y =(2x-2)+4 = 0

x = -1
y =(2x-1)+4 = 2

x = 0
y = (2x0)+4 = 4

x = 1
y =(2x1)+4 = 6

x = 2
y = (2x2)+4 = 8

Which gives you 5 sets of co-ordinates to plot: (-2,0) (-1,2) (0,4) (1,6) (2,8)

## Follow the links below to see how this topic has appeared in past exam papers

AQA Unit 2 November 2011 (F) - Page 8, Question  9

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