quadratic formula In: $ax^2 + bx + c = 0$ $x _{1,2} = (-b \pm \sqrt{b^2-4ac}) / 2a$ plug it in $x _{1,2} = (-(-2) \pm \sqrt{(-2)^2-4(1)(4)}) / 2(1)$ which equals 2 plus or minus sqrt(4-16) = 2+2(i)sqrt(3) or 2-2(i)sqrt(3) $i = \sqrt{-1}$