Question

proportionality in graphs
homework

1. *on the lines below, explain how you know whether each graph represents a

proportional relationship or not.
fig 1 fig 2 fig 3
fig 1: proportional? yes / no

fig 2: proportional? yes / no

fig 3: proportional? yes / no

Explanation:

A proportional relationship graphs as a straight line that passes through the origin (0,0), and follows the form $y=kx$ where $k$ is a constant.

1. Fig 1: The line is straight and passes through the origin, so it meets the criteria for a proportional relationship.
2. Fig 2: The line is horizontal (constant value) and does not pass through the origin, so it does not represent a proportional relationship.
3. Fig 3: The line is straight but does not pass through the origin, so it does not represent a proportional relationship.

Straight line through origin.
Fig 2: Proportional? NO

Horizontal line, no origin pass-through.
Fig 3: Proportional? NO

Straight line, no origin pass-through.

Answer:

Fig 1: Proportional? YES