# 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 -

$$y=0.75x$$