MA21-05 Maths Coming soon
Inverse proportion to a power or root
MA21-05
This lesson is coming soon.
In this lesson
Translate wording like 'inversely proportional to the square of x' into the correct algebraic form (y=k/x^2), distinguishing it from similar-sounding alternatives, before calculating anything.
What it covers
- Carefully parsing wording that combines 'inverse' with a power or root (inversely proportional to x^2, to x^3, to the square root of x)
- Distinguishing it from the direct-power/root and the inverse-linear cases by wording alone, before any calculation
- The full round-trip (already learned in the previous video) applied specifically to these harder inverse-power cases
Key words
For: Cambridge IGCSE 0580, Edexcel IGCSE 4MA1, OCR GCSE J560
On the specification
| Board | Spec | Statement |
|---|---|---|
| Cambridge IGCSE 0580 | E2.8 | Express direct and inverse proportion in algebraic terms and use this form of expression to find unknown quantities. |
| Edexcel IGCSE 4MA1 | H2.5A | Set up problems involving direct or inverse proportion and relate algebraic solutions to graphical representation of the equations |
| OCR GCSE J560 | 5.02b | Solve simple word problems involving quantities in inverse proportion or simple algebraic proportions. |
For teachers
This GCSE Maths lesson teaches inverse proportion to a power or root. By the end, students should be able to translate wording like 'inversely proportional to the square of x' into the correct algebraic form (y=k/x^2), distinguishing it from similar-sounding alternatives, before calculating anything. It works through two worked examples and the mistakes examiners report.