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

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Graphing Quadratic Equations - Problem 5

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

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One of the unique features of parabolas is that they are symmetric around the vertical line that passes through the vertex point. You can imagine a vertical "mirror line" that cuts the parabola into two halves. You can see this in a table of values, as well, provided you are clever in the way you set up your table. Here we explore how to find the x value of the vertex using x = -b/2a and put that in the middle of the table with x values on either side of it. From there, we find the corresponding y values, using symmetry as a shortcut, and graph the parabola. This trick is preferable to plugging in randomly chosen x-values because we are including the "turning point," or vertex and finding points on either side of it to complete the symmetry.

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