Straight line graphs
Plotting straight line graphs: Method 1
L. O – To be able to draw straight lines given their equation.
We can draw straight line graphs by plotting a few points.Choose 3 values of
x and work out (using the equation of the line) the corresponding y values.
You can write these in a table. Plot these 3 coordinates and draw the line!
Draw the line: y=3x +5.
Choose 3 x values; x=-2, x=2 and x=6.
Find the corresponding y values:
When x=-2 y=3(-2) +5 y=-6+5 y=-1
When x=2 y=3(2) +5 y=6+5 y=11
When x=6 y=3(6) +5 y=18+5 y=23
1. Insert the x and y values into a table.
1. Choose three x values.
2. Find the corresponding y values using the equation given ( by putting into the equation the value of x).
3. Draw up a table and insert the x and y values you have worked out above.
4. Plot the three points on a graph.
5. Join the points together to form a straight line.
2. Plot the points.
3. Draw the line.