they are
\(\frac{-b+ \sqrt{b^2-4ac} }{2a}\) and \(\frac{-b- \sqrt{b^2-4ac} }{2a}\)
we can see that we can add them because of the same denomenator and also we can see the square root bits cancel each other out
we are left with
\(\frac{-b-b}{2a}= \frac{-2b}{2a}= \frac{-b}{a}\)
the sum is -b/a
