How to graph a quadratic function

SSAT Upper Level: Quantitative · Learn by Concept

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SSAT Upper Level: Quantitative › How to graph a quadratic function

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What is the vertex of the function $f(x)=-2x^{2}-4x+7$ ?

CORRECT

$f(x)=-2x^{2}-4x+7$

The -coordinate of the vertex is $x=-\frac{b}{2a}$ , where .

$x=-\frac{b}{2a} = -\frac{-4}{2 \left (-2 \right )} = -1$

To get the -coordinate, evaluate .

$f(x)=-2x^{2}-4x+7$

$f(1)=-2 \left (-1 \right )^{2}-4\left (-1 \right )+7 =-2+4+7=9$

The vertex is .