yego.me
💡 Stop wasting time. Read Youtube instead of watch. Download Chrome Extension

Constant of proportionality from graph | 7th grade | Khan Academy


less than 1m read
·Nov 11, 2024

The following graph shows a proportional relationship. What is the constant of proportionality between y and x in the graph? Pause this video and see if you can figure that out.

All right, now let's do this together and let's remind ourselves what a constant of proportionality even is. If we know that there is a proportional relationship between y and x, then there will be a constant of proportionality between these variables. What this is, is it is a number that I would have to multiply x by to get to y.

So I could make a little table here, as we often do when we describe proportional relationships. X and y. We know that when x is 0, y is 0. But if I multiply 0 by anything, I'm going to get 0.

But then when x is 1, what is y? When x is 1, y is 3. They mark it right over there. When x is 2, what is y? X is 2, we see that y is 6.

So our constant of proportionality is what are we multiplying x by to get to y? Well, let's see. To go from one to three, I have to multiply by three. To go from two to six, I have to multiply by three.

Another way to think about it is we could write the equation y is equal to something times x. The number that we multiply x by to get y is our constant of proportionality. We’ve seen in all of these situations this should be true for any point on this line. You give the x, you multiply it by 3, you get your y.

So the relationship here is y is equal to 3x, so 3 is our constant of proportionality.

More Articles

View All
Interpreting expressions with multiple variables: Resistors | Modeling | Algebra II | Khan Academy
We’re told an electronic circuit has two resistors with resistances r1 and r2 connected in parallel. The circuit’s total resistance r sub t, or rt, is given by this formula: Suppose we increase the value of r1 while keeping r2 constant. What does the val…
The Gilded Age part 2 | The Gilded Age (1865-1898) | US History | Khan Academy
So, we were talking about the wealth inequality that characterized the Gilded Age, but you were telling me that that’s not the only thing, Kim, that characterizes this period. Right? What really makes the Gilded Age happen is what we call the Second Indus…
This is Ruining Our Lives
The year is 1665, and Isaac Newton is looking out his window at an apple tree standing tall in his orchard in Lincolnshire, England. All of a sudden, a ripe and lonely apple falls from the tree and makes its way to the ground. While most people would cons…
Are There Lost Alien Civilizations in Our Past?
When we think about alien civilizations, we tend to look into the vastness of space, to far away planets. But there is another incredibly vast dimension that we might be giving too little thought to: time. Could it be that, over the last hundreds of milli…
Externalities: Calculating the Hidden Costs of Products
What’s a mispriced externality you mentioned at some point during our podcast? An externality is when there is an additional cost that is imposed by whatever product is being produced or consumed that is not accounted for in the price of the product. Some…
2015 AP Calculus AB 5b | AP Calculus AB solved exams | AP Calculus AB | Khan Academy
Part B on what open intervals contained in -3 is less than x is less than four is the graph of F both concave down and decreasing. Give a reason for your answer. All right, so F needs to be both concave down and decreasing. So, F concave down. Concave do…