This deep dive covers Method 1: The Multiplier Method within Direct Proportion for GCSE Mathematics. Revise Direct Proportion in Ratio & Proportion for GCSE Mathematics with 15 exam-style questions and 12 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 3 of 9 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.
Method 1: The Multiplier Method
1
Find how x has changed
What did you multiply x by to get the new x?
2
Apply the same multiplier to y
In direct proportion, y changes by the same factor
Practice questions for Direct Proportion
Which of the following correctly reads the mathematical statement y ∝ x?
Explain what it means for y to be directly proportional to x. Your answer should refer to the equation and the graph.
Quick recall flashcards
What does the symbol ∝ mean?
'is proportional to'
y ∝ x means 'y is proportional to x'
This is equivalent to writing y = kx for some constant k.
What does the graph of y = kx look like?
A straight line passing through the origin (0, 0).
The gradient of the line equals k.
If the line does NOT pass through (0,0), it is NOT direct proportion.