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## Operations and Algebraic Thinking 218-221

### Course: Operations and Algebraic Thinking 218-221>Unit 5

Lesson 8: Dependent and independent variables

# Dependent & independent variables: graphing

It's helpful to express an equation on a graph where we plot at least 2 points. Watch and we'll show you. Created by Sal Khan.

## 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.