Dependent & independent variables: graphing
About this video
On a quiz you earn 5 points per correct answer, so the score is y = 5x. The video graphs this by plotting points such as (0, 0) and (1, 5) and notes that two points are enough to define a line.
You'll be able to
- find points that fit an equation like y = 5x.
- plot points from an equation on a graph.
- explain why two points are enough to draw a line.
Key words
- independent variable
- Here x, the number of questions you get right, which you can choose.
- dependent variable
- Here y, the total points, which depends on how many you get right.
- point
- A pair of values (x, y) that you mark on a graph.
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.
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