A constant of variation, also known as a constant of proportionality, is a non-zero constant that relates two variables.
Direct Variation
In a direct variation, the constant of variation k represents the ratio of two variables. The ratio remains unchanged when the variables x and y change.
xy=k,wherex=0andy=0
When the variable y is isolated on the left-hand side, the constant of variation k defines the slope of the line through the origin that represents the relationship between x and y.
xy=k⇔y=kx
Inverse Variation
In an inverse variation, the constant of variation k is the product of two variables. The product remains the same when the variables x and y change.