Answer
$
-\frac{b}{a}$
Work Step by Step
Adding the two solutions of the Quadratic Formula results to
\begin{array}{l}\require{cancel}
\dfrac{-b+\sqrt{b^2-4ac}}{2a}+\dfrac{-b-\sqrt{b^2-4ac}}{2a}
\\\\=
\dfrac{-b+\sqrt{b^2-4ac}+(-b-\sqrt{b^2-4ac})}{2a}
\\\\=
\dfrac{-b+\sqrt{b^2-4ac}-b-\sqrt{b^2-4ac}}{2a}
\\\\=
\dfrac{-2b}{2a}
\\\\=
\dfrac{-\cancel{2}b}{\cancel{2}a}
\\\\=
-\dfrac{b}{a}
.\end{array}
Hence, the sum of the two solutions is $-\dfrac{b}{a}$.
