GraphsKey Facts

Working with y = mx + c

Part of y = mx + cGCSE Mathematics

This key facts covers Working with y = mx + c within y = mx + c for GCSE Mathematics. Revise y = mx + c in Graphs for GCSE Mathematics with 10 exam-style questions and 20 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 6 of 9 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.

Topic position

Section 6 of 9

Practice

10 questions

Recall

20 flashcards

Working with y = mx + c

Finding the Equation from a Graph

  1. Find c: Read where the line crosses the y-axis
  2. Find m: Choose two clear points and use m = (y₂ - y₁)/(x₂ - x₁)
  3. Write equation: Substitute m and c into y = mx + c

Finding the Equation from Two Points

  1. Calculate gradient: m = (y₂ - y₁)/(x₂ - x₁)
  2. Substitute one point: Use y = mx + c with known m and one point
  3. Solve for c: Rearrange to find the y-intercept
  4. Write final equation

Finding Points on the Line

  • Given x, find y: Substitute x into y = mx + c
  • Given y, find x: Rearrange y = mx + c to solve for x

Keep building this topic

Read this section alongside the surrounding pages in y = mx + c. That gives you the full topic sequence instead of a single isolated revision point.

Practice Questions for y = mx + c

For the line y = 3x – 2, what is the gradient?

  • A. –2
  • B. 3
  • C. 2
  • D. –3
1 markfoundation

Two students write down equations for parallel lines: Student A writes: y = 2x + 1 Student B writes: y = 2x + 1 Explain why these two lines are NOT parallel to each other.

2 markshigher

Quick Recall Flashcards

What gradient gives a 45° line?
m = 1 (rises 1 unit for every 1 unit across)
What is special about y = mx?
It passes through the origin (0, 0) because c = 0.

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