x36912 y1234 State whether the table shows a direct variation. Prove it in two ways. x46810 y The variables x and y vary directly. Use the values of x and y to find a constant of proportionality. Then write an equation that relates x to y. y = 3 and x = 4
CoCo Puffs Marsh- mallows General Mills is coming out with a new cereal called Hot Cocoa. They experimented with some samples to decide their recipe. We will chart to samples What would the equation be?
Identifying Direct Variation Origin (0,0) Constant SLOPE Or check if the values form a proportion
If four Oreo cookies contain 220 calories. How many calories would be consumed if you eat three? Find the constant variation first. Write and use the equation to solve for three cookies.
The variables x and y vary directly. Use the values to find the constant of proportionality and write an equation that relates x and y. 9. y = kx K is for constant
xy If it goes through (0,0) The slope The change in y The change in x y = kx k =
xy Oh No! There is no 0! Oh No! There is no 0! xy Relax. We’ll make a space for one xy You try!
I wish everyone would go home and leave me alone! Rearranging Equations (Changing the Point-of-View) Solve for y: What is happening on the side with y? _______________________ What is the opposite? ______________________ x + y = 3
I wish everyone would go home and leave me alone! 4x + y = 7x
Can the equation be written y = kx? Only combine LIKE terms y = -4x y − 2x = x y − 5 = 5x + 2 y − 2 = 3x − 2 y + 3 = x xy = 5
Miles driven Gallons Gas used Is this a proportional relationship? Prove it in two ways