Algebraic ratios
I can form equations from algebraic ratios and solve to find an unknown.
Algebraic ratios
I can form equations from algebraic ratios and solve to find an unknown.
Lesson details
Key learning points
- Equivalent ratios have a scalar multiplier.
- Two equations can be written which are simultaneous.
- This can be set equal to each other and then solved.
Common misconception
When $$x : y$$ are in the ratio 1 : 2 pupils write the equation as $$x = 2y$$
Show that the equation $$x = 2y$$ in a ratio table would mean the multiplier from $$y$$ to $$x$$ would be times by 2, this would mean when $$y=1 x=2$$ which is 2 : 1 not 1 : 2
Keywords
Proportionality - Proportionality means when variables are in proportion if they have a constant multiplicative relationship.
Ratio - A ratio shows the relative sizes of 2 or more values and allows you to compare a part with another part in a whole.
Factorise - A ratio shows the relative sizes of 2 or more values and allows you to compare a part with another part in a whole.
Licence
This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).
Video
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Starter quiz
6 Questions
3 : 1 -
$$y={1\over3}x$$
1 : 3 -
$$y=3x$$
4 : 5 -
$$y=1.25x$$
5 : 4 -
$$y=0.8x$$
4 : 3 -
$$y=0.75x$$