Maths Library

Linear graphs and gradient: Year 9 maths

This topic explores linear functions, calculating gradients, and interpreting the equation y = mx + c. The worksheet provides practice in finding slopes, determining intercepts, and sketching or identifying lines.

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What this covers

Linear graphs and gradient is taught in Year 9 (age 14 to 15) as a main teaching focus. It sits in the Algebra strand.

Worked example

Find the gradient of the line passing through (1, 3) and (5, 11).

  1. Use the gradient formula: m = (y2 - y1) ÷ (x2 - x1)
  2. Substitute the coordinates: m = (11 - 3) ÷ (5 - 1)
  3. Simplify the fraction: m = 84 = 2

Answer: 2

Difficulty scale

The sheet generator offers five difficulty settings for this topic.

  1. Reading the gradient and y-intercept directly from y = mx + c
  2. Calculating positive integer gradients from two coordinates or a drawn line
  3. Calculating negative or fractional gradients and writing equations of lines
  4. Rearranging implicit equations into y = mx + c format, e.g., 2y - 4x = 8
  5. Finding equations of lines parallel or perpendicular to a given line

Common mistakes

  • Inverting the gradient formula to run over rise: (x2 - x1) / (y2 - y1)
  • Misidentifying the gradient when the equation is not written with y as the subject

Curriculum links

Indicative matches to Australian Curriculum v9. Check wording and codes against the official document.

  • AC9M9A04 Graph linear relations on the Cartesian plane, determining gradients and intercepts.

Sample sheet and answers

Six questions at the level's usual difficulty. Open the editor to change, add or regenerate any of them.

Linear graphs and gradient

Year 9 maths

Qs
6
Marks
12
NameDateScore / 12
1.
Write the equation of the line in the form y = mx + c.
-5-5-4-4-3-3-2-2-1-11122334455
[2]
2.
Write the equation of the line in the form y = mx + c.
-5-5-4-4-3-3-2-2-1-11122334455
[2]
3.
Write the equation of the line in the form y = mx + c.
-5-5-4-4-3-3-2-2-1-11122334455
[2]
4.
Write the equation of the line in the form y = mx + c.
-5-5-4-4-3-3-2-2-1-11122334455
[2]
5.
Write the equation of the line in the form y = mx + c.
-5-5-4-4-3-3-2-2-1-11122334455
[2]
6.
Write the equation of the line in the form y = mx + c.
-5-5-4-4-3-3-2-2-1-11122334455
[2]

Answer key

  1. y = −2x + 4The line crosses the y-axis at 4, so c = 4; It goes −2 up for each 1 across, so m = −2
  2. y = −x + 3The line crosses the y-axis at 3, so c = 3; It goes −1 up for each 1 across, so m = −1
  3. y = −3x − 1The line crosses the y-axis at −1, so c = −1; It goes −3 up for each 1 across, so m = −3
  4. y = x − 2The line crosses the y-axis at −2, so c = −2; It goes 1 up for each 1 across, so m = 1
  5. y = 2x + 3The line crosses the y-axis at 3, so c = 3; It goes 2 up for each 1 across, so m = 2
  6. y = 3x + 1The line crosses the y-axis at 1, so c = 1; It goes 3 up for each 1 across, so m = 3