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## Pre-algebra

### Unit 7: Lesson 8

Dependent and independent variables# Dependent & independent variables: graphing

CCSS.Math:

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.