Drawing-Straight-Line-Graphs Aqa Higher

Drawing linear graphs

How do I draw a straight line from a table of values?

• You may be given a table of values with no equation

• Use the x and y values to form a point with coordinates (x, y)

  • Then plot these points

  • Use a ruler to draw a straight line through them 

    • All points should lie on the line

• For example 

  • The points below are (-3, 0), (-2, 2), … etc

How do I draw a straight line using y = mx + c?

• Use the equation to create your own table of values

  • Choose points that are spread out across the axes given

• For example, plot y = 2x + 1 on axes from x = 0 to x = 10

  • Substitute in x = 0, x = 5 and x = 10 to get y coordinates

    • Then plot those points

How do I draw a straight line without using a table of values?

• Assuming the equation is in the form y = mx + c

• Start at the y-intercept, c

• Then, for every 1 unit to the right, go up m units

  • m is the gradient

  • If m is negative, go down

  • If m is a fraction, remember that gradient is change in y divided by change in x

    • A gradient of would be units up for every units right

• This creates a sequence of points which you can then join up

  • Be careful of counting squares if axes have different scales

    • 1 unit might not be 1 square

What if the equation is not in the form y = mx + c?

• Equations will not always be presented in the form y = mx + c

• Rearranging to y = mx + c will make plotting these graphs easier

• Consider the equation

  • Subtract 3x from both sides

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