Khan Academy: Algebra: Proportionality Constant for Direct Variation

Once learners realize what direct variation is, they see it's just a type of linear function. The lesson poses a general question that leads to the creation of the y = kx formula. The resource includes discussion prompts and ideas for...

This video solves a basic direct variation problem: the cost of buying gas for your car varies directly with the number of gallons you need to purchase. Sal shows how to write a direct variation equation based on this problem and solves...

Use the formula for direct variation to solve for y, after finding the value of k. When you use the formula and determine the value of k and x, you can plug in those values to determine the value of y. A quick tutorial that takes you...

y=kx. This is the direct variation equation. You have been given a table of values. So look at the table and figure out how to use this equation to write an equation that represents what is happening in the table. Does the equation...

This problem may sound a bit confusing, but the teacher does a great job explaining what direct variation is. So watch this video and learn about k. It is a pretty direct explanation.

This video demonstrates how to solve a word problem involving a direct variation. It shows how to set up a linear equation for a directly proportional relationship and solve for the constant of proportionality. [2:02]

This video demonstrates how to create a direct variation model, or a linear equation, given a word problem that deals with rate of change. It also shows how to solve the equation and graph the direct variation model. Practice problems...

Direct variation? Constant of variation? Constant of proportionality? Two variables related? If one variable changes what happens to the other variable? What do all these terms have to do with each other? Watch this video as the...

In a graph of a direct variation, the line must pass through the origin, (0,0). See the teacher illustrate what that looks like on a graph.

In a graph of a direct variation, the line must pass through the origin, (0,0). See the teacher illustrate what that looks like on a graph.