Proportionalities
relationships between variables
If y is directly proportional to x, this can be written as
y ∝ x. The equation relating the two variables is y=kx where k is a constant. To easily see direct proportionality from an equation, rearrange it so that the variables are on either side of the = sign. If both variables are on the top line, then they have a directly proportional relationship. |
If y is inversely proportional to x, this can be written as
y ∝ 1/x. The equation relating the two variables is y=k/x where k is a constant. To recognise an inversely proportional relationship, rearrange with the desired variables on either side of the = sign and look for one variable on the top line and the other on the bottom. |
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