Two variables are inversely proportional if there is a constant multiplicative relationship between one variable and the reciprocal of the other.

Two variables are in direct proportion if they have a constant multiplicative relationship.

Proportion modelled algebraically

Maths

In the linear graphs unit, pupils learnt to recognise and interpret graphs that illustrate direct and inverse proportion. In this unit, pupils learn how to represent these relationships algebraically.

Direct and inverse proportion

Which of the following show an inversely proportional relationship between $$y$$ and $$x^n$$?

Which of these graphs show direct proportion between $$y$$ and $$x^n$$?

Two variables are inversely proportional if there is a constant {{}} relationship between one variable and the reciprocal of the other. 

Match the value of $$k$$ with the relevant graph for $$y=\frac{k}{x}$$

Match the value of $$k$$ with the relevant graph for $$y=\frac{k}{x^2}$$

Which of the following equations of a line show the direct proportion between $$x$$ and $$y$$?

Which of the following equations of a curve show the direct proportion between $$x^2$$ and $$y$$?

Which of the following show that $$x$$ is inversely proportional to $$y$$?

 Given that $$y$$ is directly proportional to $$𝑥$$ and $$𝑦=30$$ when $$x=5$$, write the equation connecting $$y$$ and $$x$$.

Given that $$y$$ is directly proportional to $$𝑥^2$$ and $$𝑦=4375$$ when $$x=25$$, write the equation connecting $$y$$ and $$x^2$$.

 Given that $$y\propto \frac{1}{𝑥}$$ and $$𝑦=4$$ when $$x=50$$, write the equation connecting $$y$$ and $$x$$.

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Proportion modelled algebraically

Lesson outcome