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 The graph of the equation $y =ax^2 + bx + c$, where $a$, $b$, and $c$ are constants, is a parabola with axis of symmetry $x = -3.$ Find $\frac{b}{a}$.

 Jun 16, 2018
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How are you doing today, Lightning?

 

You may know that you can determine the equation of the axis of symmetry of any parabola by knowing that \(x=\frac{-b}{2a}\) . In this case, the axis of symmetry is already given: \(x=-3\) .

 

Since \(x=-3\) and \(x=\frac{-b}{2a}\)\(\frac{-b}{2a}=-3\) . The only task left is to solve for b/a .

 

\(\frac{-b}{2a}=-3\) Multiply by 2 on both sides. 
\(\frac{-b}{a}=-6\) We are almost there! Multiply by -1 to inverse the sign.
\(\frac{b}{a}=6\) There you go!
 Jun 17, 2018

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