Mathematic Test
When $- a \ne 0 -$, there are two solutions to $- ax^2 + bx + c = 0 -$ and they are $$x = {-b \pm \sqrt{b^2-4ac} \over 2a}.$$
When $- a \ne 0 -$, there are two solutions to $- ax^2 + bx + c = 0 -$ and they are $$x = {-b \pm \sqrt{b^2-4ac} \over 2a}.$$