Straight-line graphs
Lesson 12 of 13
Plotting lines from an equation
Objective. Plot a straight line by making a small table of values.
The key idea
Choose three x-values, substitute to find y, plot and join. Three points let you spot an arithmetic slip.
Worked example
Plot y = 2x − 1 for x = 0, 1, 2.
- 1x = 0 gives y = −1.
- 2x = 1 gives y = 1.
- 3x = 2 gives y = 3. Points: (0,−1), (1,1), (2,3).
Answer: A line through (0, −1) with gradient 2
Practice
Each question comes with a picture and a listen button. Try it first, then reveal the answer.
Common mistake. Joining only two points and never noticing a mis-plot.
Your progress
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