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- Graphing proportional relationships from an equation
- Graphing proportional relationships
Graphing proportional relationships from an equation
Sal graphs the equation of a line that represents a proportional relationship given an equation. Created by Sal Khan.
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- i still don't understand how to do these :((28 votes)
- First start with an equation, like y = 4x. Next, plug in a number as x, like 5. Since you would need to multiply it by 4 to find y,(hence the 4x), That means that the y would be equal to 20.
So, in the end, a point on your graph would be (5,20). To find other points, you would plug in any other number as x, and that would get you your line.
Does that help?(4 votes)
- dude i dont u n d e r s t a n d, please help(16 votes)
- I don't get any of this. PLZ help!(12 votes)
- i like chicken(8 votes)
- i dont understand(6 votes)
- How can I help you? Reply back please.(6 votes)
- I look in the question bar for help and everyone's as lost as I am.(4 votes)
- Plus all these comments are ancient, no one from my class is active on here apparently. They probably need to get upvoted to be seen so I don't think anyone's reading my comments either.(10 votes)
- At2:50, how can Y change 12.5?(6 votes)
- At2:50Y doesn't change 12.5 it changes by 5 for every time the x changes by 1(3 votes)
- is math related to science(1 vote)
- Yes, you will encounter a lot of mathematical equations and calculations in chemistry and physics.
Have a blessed, wonderful day!(12 votes)
- If you read this your a dad(6 votes)
We're asked to graph y is equal to 2.5 times x. So we really just have to think about two points that satisfy this equation here, and the most obvious one is what happens when x equals 0. When x equals 0, 2.5 times 0 is going to be 0. So when x is 0, y is going to be equal to 0. And then let's just pick another x that will give us a y that is a whole number. So if x increases by 1, y is going to increase by 2.5. It's going to go right over there, and I could graph it just like that. And we see just by what I just said that the unit rate of change of y with respect to x is 2.5. A unit increase in x, an increase of 1 and x, results in a 2.5 increase in y. You see that right over here. x goes from 0 to 1, and y goes from 0 to 2.5. But let's increase x by another 1, and then y is going to increase by 2.5 again to get to 5. Or you could say, hey, look, if x is equal to 2, 2.5 times 2 is equal to 5. So this is a legitimate graph for this equation, but then they also tell us to select the statements that are true. So the first one is the equation does not represent a proportional relationship. Well, this is a proportional relationship. A proportional relationship is one where, first of all, if you have zero x's, you're going to have zero y's, where y is equal to some constant times x. And here, y is equal to 2.5 times x. So this is definitely a proportional relationship, so I'm not going to check that. The unit rate of the relationship is 2/5. So I'm assuming-- this is a little ambiguous the way they stated it. I'm assuming they're saying the unit rate of change of y with respect to x. And the unit rate of change of y with respect to x is, when x increases 1, y changed 2.5. So here they're saying when x changes by 1, y changes by 0.4, 2/5 is the same thing as 0.4. This should be 5/2. 5/2 would be 2.4. So this isn't right as well. The slope of the line is 2.5. Well, this looks right. Slope is change in y over change in x. When x changes 1, y changes 2.5. So change in y, 2.5, over change in x, 1. 2.5 over 1 is 2.5. And you could also see it looking at the form of this equation. y is equal to-- this is the slope times x. So that's right. A change of 5 units in x results in a change of 2 units in y. Well, let's test that idea. We know when x is 0, y is 0. So if x goes from 0 to 5, what's going to happen to y? Well, y is going to be 2.5 times 5. 2.5 times 5 is 12.5. So y would not just change 2. It actually would change 12.5. So this isn't right. A change of 2 units in x results in a change of 5 units in y. Well, we see that. A change in 2 units of x results in a change of 5 units in y. That's exactly what we graphed right over here. These two points show that. So this is definitely true.