Substitute numbers in it and you get the solution, for any solvable quadratic equation :)
\(\underline{\text{Quadratic Formula}}\\ \text{For any quadratic equation } ax^2 + bx + c = 0\\ \text{The solutions for x are } \dfrac{-b+\sqrt{b^2-4ac}}{2a}\text{ or }\dfrac{-b-\sqrt{b^2-4ac}}{2a}\)
If you see any negative numbers in it:
\(x^2 - 7x + 6\)<--- like this one
Turn it into: \(x^2 + (-7)x + 6\) <-- that way it will be exact same as the general form and you can substitute numbers :D