1
Write the equation: y = kx (or y = kx² for Higher)
2
Substitute given values to find k
3
Rewrite formula with the k value
4
Use your formula to find missing values
This deep dive covers Method: Finding the Constant within Proportion Graphs for GCSE Mathematics. Revise Proportion Graphs in Ratio & Proportion for GCSE Mathematics with 14 exam-style questions and 4 flashcards. Use this page as part of a wider topic revision path rather than treating it as an isolated fact. It is section 3 of 6 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.
Practice questions for Proportion Graphs
Which of the following describes the graph of a direct proportion relationship?
Aisha says: 'Because the graph of y against x is a straight line, y must be directly proportional to x.' Is Aisha correct? Explain your answer.
Quick recall flashcards
Finding k
Use given values to find constant k, then apply to new values
Direct vs Inverse
Direct: both increase together (y ∝ x). Inverse: one increases, other decreases (y ∝ 1/x).