The equation expressing the statement "y varies directly as x" is
Explanation
The statement that varies directly as
is analogous to saying that the ratio of
to
is constant. In other words, when
increases,
likewise increases and that when
decreases,
decreases proportionally.
Mathematically, we express the relationship that the ration of is to
is constant is expressed as;
where
is the constant of proportionality.
We can then solve the relationship for to determine the correct form of the relationship as shown below,