This key facts covers Key Facts within Proportion Graphs for GCSE Mathematics. Revise Proportion Graphs in Ratio & Proportion for GCSE Mathematics with 14 exam-style questions and 4 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 2 of 5 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 2 of 5
Practice
14 questions
Recall
4 flashcards
Key Facts
| Symbol | y ∝ x means "y is directly proportional to x" |
| Formula | y = kx, where k is the constant of proportionality |
| Graph | A straight line through the origin (0,0) |
| Key Feature | y/x always equals the same value (k) |
| Higher: y ∝ x² | y = kx² (quadrupling x means y × 4²) |