01 — Explanation
How do I turn an equation into a table of values?
Choose a spread of -values (usually given in the question, e.g. to ), then substitute each into the equation to get the matching -value. For :
02 — Explanation
How do I plot the line accurately?
Plot each pair as a point, then join them with a single, ruled, straight line extending across the full grid — not just dot-to-dot between the plotted points. If one plotted point doesn't sit on the same line as the rest, you've made an arithmetic error and should recheck that value.
03 — Explanation
What if the equation isn't already in the form y = \ldots?
Some equations are given implicitly, e.g. . Rearrange for first so you can substitute cleanly:
Then build the table exactly as before. Choosing -values that are multiples of the denominator (here, even numbers) often keeps the -values as whole numbers or simple fractions, which makes plotting far less error-prone.
04 — Explanation
What if no x-range is given to me at all?
If the question doesn't specify a range, pick values that keep the table manageable and centred near the origin — typically five or six integers such as . Avoid huge values that would force an awkwardly-scaled grid; the goal is a clear, evenly-spaced set of points that reveal the line's direction.
05 — Explanation
How do I recognise and draw a horizontal or vertical line?
An equation like has the same -value for every , so it's a horizontal line through on the -axis — no table is even needed. Likewise is a vertical line through on the -axis. These are easy to lose marks on if you try to force them into a sloped-line table by mistake.
Exam tip
Examiners check plotted points to within half a small square. If your line doesn't pass through all your table values, don't force a "best fit" line through them — a straight-line graph must be exact, so go back and find your arithmetic mistake.
06 — Worked example
Worked example
Draw the graph of for .
- Substitute each integer from to :
- Plot .
- Draw one ruled straight line through all five points, extending slightly beyond the first and last point.
07 — Worked example
Worked example: an implicit equation
Draw the graph of for .
- Rearrange for : .
- Choose multiples of to keep a whole number: ; ; .
- Plot and draw one ruled line through them, extending across the grid.