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The Vertex and Axis of Symmetry  Problem 1
Alissa Fong
Alissa Fong
MA, Stanford University
Teaching in the San Francisco Bay Area
Alissa is currently a teacher in the San Francisco Bay Area and Brightstorm users love her clear, concise explanations of tough concepts
Finding the vertex from a graph is really easy. You just look for the highest or lowest point of a parabola. Finding the vertex from an equation is a little trickier. You do have to remember how to find the x coordinate. The way to find the x coordinate and that’s your first step is to find b/2a. Once you’ve found that value, you’re going to substitute it back in to find your corresponding y value.
Here is what I mean, b/2a in this situation is going to be 6 over 2 times 1 which is equal to 3. That tells me the first or x coordinate of my vertex is going to be 3. To find the y value, I need to plug in 3 for my x substituting and find the corresponding y. Y is going to be 3 squared plus 6 times 3 plus 8. Do that out, I’ll have 9 take away 18 plus 8, moving from left to right, that’s 9 plus 8 which is 1. Okay there we go. That’s the Vertex for my parabola. I’m done with the problem.
If I wanted to I can graph that to verify, or if I had to make a graph to begin with, I know this parabola opens up and the vertex, or the lowest point is (3,1). So I already in my head can kind of visualize that this parabola is going to look something like that.
So this is how a vertex can be useful if you have to graph something, you start by finding the x coordinate, you find the corresponding y value, and it helps you wrap your head around what the sketch of that parabola might look like.
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Alissa Fong
M.A. in Secondary Mathematics, Stanford University
B.S., Stanford University
Alissa has a quirky sense of humor and a relatable personality that make it easy for students to pay attention and understand the material. She has all the math tips and tricks students are looking for.
Your tutorials are good and you have a personality as well. I hope you have more advanced college level stuff, because I like the way you teach.”
Thanks alot for such great lectures... I never found learning this easier ever before... keep up the great work.... :)”
You seem so kind, it's awesome. Easier to learn from people who seem to be rooting for ya!' thanks”
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