Quadratic Equations and Functions
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
In exploring parabolas, we find that the all have a lot of key features in common: they all are symmetric around a vertical line that has the equation x = -b/2a. It is called the axis of symmetry. If you plug that x value back into the function, you get the y-coordinate of the vertex. The vertex is always the maximum or minimum y-value on a parabola. The vertex is particularly important in quadratic word problems. The y intercept is always the point when x is zero. The x-intercept(s) are found when y is zero using a variety of possible methods. There could be zero, one, or two x-intercepts.
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