How to answer an inverse proportion question (y is inversely proportional to x², and y = 2 when x = 3. Find y when x = 2)
1. Write it with k: y ∝ 1/x² → y = k/x²
2. Put in the pair you are given and find k: 2 = k/3², so k = 18
3. Write the formula with the number for k, then substitute: y = 18/x², x = 2 → y = 18/4 = 9/2
Level up: with the same formula y = 18/x², find y when x = 6.
Your turn is in the pinned comment.
Road to A* follows the IGCSE 0580 course in order, one concept per episode. This is episode 35.
For: IGCSE 0580 E2.8 Proportion (Extended) · GCSE
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