When two variable quantities have a
constant (unchanged) ratio,
their relationship is called a direct
It is said that one variable "varies directly" as the
ratio is called the constant of variation.
The formula for
direct variation is y = kx,
is the constant of variation.
"y varies directly as x"
Solving for k:
numerator; x = denominator)
In a direct variation, the two
change in the same sense. If one increases, so does the other.
Graphically, direct variation y
= kx when k > 0.
As x increases, y increases.
The weekly salary a woman earns, S, varies directly as the number of
hours, h, which she works. Express this relation as a formula.
is the constant)