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Vertex Form

The following equation for a quadratic function:

is written in “Vertex Form”.


(h, k) – Coordinates of the Vertex of the Parabola

x – Location of the Axis of Symmetry

a – indicates the width and direction (up or down) of the Parabola

When a is positive, the parabola opens upwards. When a is negative, the parabola opens downwards. As a increases its distance from zero, the parabola becomes narrower.

Figure 1.

-The graph moves |h| units left if h is negative or |h| units right if h is positive.

-The graph moves |k| units up if k is positive, or |k| units down if k is negative.

Below is a graph of a quadratic function in vertex form:

Figure 2.

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