Proportional Relationships
Two quantities are proportional if one of them is obtained by multiplying the other by a constant number called the constant of proportionality (k).
It can be expressed as:
[tex]y=k\cdot x[/tex]
The equation above is the equation of a line and it has one special feature: it must pass across the origin (0,0). You can recognize if a graph represents a proportion if:
* The graph is a line
* It passes through the origin
Only one of the given graphs fulfills both conditions, Graph a.
