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Course: SAT > Unit 10

Lesson 2: Passport to advanced mathematics

Nonlinear equation graphs — Basic example

Watch Sal work through a basic Nonlinear equation graphs problem.

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Video transcript

- [Instructor] We're told the graph of Y is equal to three X squared minus 12 X plus nine is shown right over here. If the graph crosses the Y axis at the point 0,K, what is the value of K? Pause this video and see if you can work through this. All right. So the graph crosses the Y axis at the point 0. So the X coordinate is zero. Y coordinate is K. So it's at this point, right over here. We would also call that the Y intercept, which is the Y value when the X coordinate is equal to zero. And to figure that out we just have to look back to the equation. I'll just rewrite it. Y is equal to, and we see that it's written in standard form, three X squared, minus 12 X plus nine. And so what is Y going to be equal to when X is equal to zero? Well, when X equals zero, that term's just going to be zero. When X is equal to zero this term's going to be equal to zero. And so Y is going to be equal to nine. And that is choice C and we're done.