Graphing Proportional Relationships

Which of the equations below is proportional?

• y = 6x

• y = 3x + 2

• y = 2x + 4

• y = -2x -1

Will the graph of a proportional relationship go through the origin?

• Always

• Sometimes

• Never

Answer explanation

Proportional graphs ALWAYS pass through or start at the origin.

Is this graph proportional?

• No, it passes through the origin

• No, it is a single straight line

• Yes, it passes through the origin and is a single straight line

Which variable is represented by the horizontal axis?

• x

• y

• z

• The origin

Answer explanation

x is the horizontal axis, y is the vertical axis.

What tells us this is not a proportional graph?

• We don't know what number it starts at.

• It does not start at the origin

• But it IS proportional!

Proportional?

• Yes,

• No, its facing the wrong way

The constant of proportionality is the same as...

• the origin

• the y-intercept

• the unit rate

All proportional Relationships... (select all correct answers)

• Go through the origin

• compare an x and a y on a graph

• have a constant slope

What is the constant of proportionality?

• 3 feet per minute

• 6 feet per minute

• 1 minute per 3 feet

• 1 minute per 6 feet

The constant of proportionality and the slope are the same thing.

• True

• False