When factoring stalls, the formula does not: $x = \dfrac{-b \pm \sqrt{b^2 - 4ac}}{2a}$. Read aloud: x equals minus b, plus or minus the square root of b-squared minus four a c, all over two a — a formula you can say is a formula you own. The ± is two answers in one line: a plus branch and a minus branch, one for each root.

With a positive, plus digs out the LARGER root and minus the smaller — the branches never trade places. Two disciplines settle almost every mark: the whole crown, −b and square root together, sits over 2a — all of it; and b walks in wearing its own sign, so for $x^2 - 6x + 8$ the formula opens with $-b = +6$. Most formula wounds are sign wounds.