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### Course: Pre-algebra > Unit 7

Lesson 8: Dependent and independent variables# Dependent & independent variables: graphing

When you answer math quiz questions, each correct answer earns you 5 points. The number of correct answers (x) and total points (y) are related by the equation y = 5x. This relationship can be visualized on a graph. Created by Sal Khan.

## Want to join the conversation?

- i have a question over some of the stuff i am doing right now. comparing lines like figuring out stuff like for example.. y= x-1 and you have 3 lines and you have to figure out which one matches up with that. i find that very confusing. can someone help me?(16 votes)
- Begin by taking some 𝑥-values and figure out what their corresponding 𝑦-values should be.

Example: 𝑦 = 𝑥 − 1

𝑥 = 1 ⇒ 𝑦 = 0

𝑥 = 2 ⇒ 𝑦 = 1

𝑥 = 3 ⇒ 𝑦 = 2

Now you graph the points (1, 0), (2, 1) and (3, 2) to see which one of the lines they belong to.(24 votes)

- I don't understand the independent dependent varbials im stuck can someone explain this and how can you tell which is which(8 votes)
- Independent variables are not affected by external factors. For example, Tommy runs 7 meters/second. In this example, there are two variables; time and distance. In order to find which one is independent and which one is dependent, we need to think logically. Is time affected by distance or is distance affected by time? The correct answer is the distance is affected by time. If Tommy ran for 2 seconds, he would run 14 meters. Whatever is being affected by another variable is the dependent variable. The variable changing another variable but cannot be changed by another variable is called the independent variable. An easy way to remember this is to think of it this way; Independent means by itself (rough definition) and dependent means (relying on something). Again, whatever is affected by another variable is the dependent variable because it relies on the value of the other variable. A variable that isn't determined by another variable's value is an independent value. If you're still confused, don't hesitate to ask. I hope this helped!(22 votes)

- this was to quick can you make a new video but slower(6 votes)
- you could make the video slower if you want(7 votes)

- i dont still understantd how to answer the question on the quiz(8 votes)
- Im stuck i don't understand at0:15already.. its confusing(4 votes)
- What he was trying to show was that, using the table above, you can plot at least two points on the graph. Since it's about getting points on each correct answer, you should know that there can't be any negative answers. There are x and y coordinates, which I think you know by now.

x= 1 (Correct Answer) and y=5 (Points)

So the graph there shows that you can plot two points. One I already gave you, which is (1,5), and the next one is (2,10).

Hope this helped.(8 votes)

- the biggest thing that confuses me on here is using decimals and I get even more lose when using them in fractions and I can't find a vid to clear that up could someone please help me?(5 votes)
- Can’t you just convert fractions to decimals?(2 votes)

- how do i make the equations I don't understand(5 votes)
- Khanacademy, can u make a 10 minute video of this again? I’m getting so confuse.(4 votes)
- It'll be easier the more you practice. I recommend rewatching it!(2 votes)

- I have still no idea how to get the independent variable for a graph.(4 votes)
- i dont know how to figure out the graph(3 votes)

## Video transcript

On your math quiz, you earn
5 points for each question that you answer correctly. In the table below, x represents
the number of questions that you answer correctly, and
y represents the total number of points that you
score on your quiz. Fair enough? The relationship between
these two variables can be expressed by the
following equation-- y is equal to 5x. Graph the equation below. So you could look at a
couple of your points. You could say, well, look,
if I got 0 questions right I'm going to have 0 points. So you could literally
graph that point-- if I got 0 questions
right, I get 0 points. And then if I get
one question right, and the table tells us
that, or we could logically think about it, every
question I would get right I'm going to get 5 more points. So if I get one question right,
I'm going to get 5 more points, and we saw that in
our table as well. We saw that right over here--
one question, 5 points. We could also plot it
two questions, 10 points, any of these. But you only have to do two
points to define a line. So it looks like we
are actually done here.