Direct & Inverse Variation
Direct variation describes a simple relationship between two variables . We say varies directly with (or as , in some textbooks) if:
for some constant .
This means that as increases, increases and as decreases, decreases—and that the ratio between them always stays the same.
The graph of the direct variation equation is a straight line through the origin.
Direct Variation Equation
for
different values of
Inverse variation describes another kind of relationship. We say varies inversely with (or as , in some textbooks) if :
,
or, equivalently,
for some constant .
This means that as increases, decreases and as decreases, increases.
The graph of the inverse variation equation is a hyperbola .
Inverse Variation Equation
for
different values of