Direct Proportion Graphing

Y varies directly as x. If y = 12 when x = 15, what is y when x = 20?

• 4/5

• 17

• 16

• 25

Which equation exhibits a direct proportion?

• y = 5x - 2

• y = 3/4 x

• y - x = 4

• x = 6

For an equation to be directly proportional, it must .......

• pass thru two points

• pass thru the origin

• be positive

• not have a fraction

Upon seeing, "y varies directly as x" we immediately.....

• write down what x and y are

• write down what k is equal to

• substitute into the equation

• write y = kx

Is this graph proportional?

• Yes

• No

Graph the equation

y=3x

The Bountiful Harvest Festival awarded Kimberly and her dad first prize for their garlic fries last year, so they're making them again this year. The key to their success is using fresh potatoes.

It takes Kimberly 4 minutes to peel each potato.

There is a proportional relationship between the number Kimberly peels, x, and the amount of time (in minutes) it takes to peel that many potatoes, y.

Graph this relationship.

Select two points to draw a line.

Graph the equation

y=3/5x

The Bountiful Harvest Festival awarded Kimberly and her dad first prize for their garlic fries last year, so they're making them again this year. The key to their success is using fresh potatoes. It takes Kimberly 4 minutes to peel each potato. There is a proportional relationship between the number of potatoes Kimberly peels, x, and the amount of time (in minutes) it takes to peel that many potatoes, y. Graph this relationship. Select two points to draw a line.