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Vertex Form and Coordinates of the Vertex

9.10.6 Vertex Form and Coordinates of the Vertex

9.10.6 • Vertex Form and Coordinates of the Vertex

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1.

A quadratic function is defined by the expression x2−20x+19x2−20x+19.

Rewrite the expression in vertex form (of a quadratic expression) and give the coordinates of the vertex (of a graph). Show your reasoning.

Compare your answer:

(x−10)2−81(x−10)2−81. The vertex is at (10,−81)(10,−81).

x2−20x+19x2−20x+19

x2−20x+100+19−100x2−20x+100+19−100

x2−20x+100−81x2−20x+100−81

(x−10)2−81(x−10)2−81