If $$x^2−7x+12=0$$, what are the roots?

Roots of a quadratic equation $$ax^2\ +\ bx\ +\ c\ =\ 0$$ can be calculated using the formula,

Roots $$=\ \dfrac{-b\ \pm\ \sqrt{\ b^2\ -\ 4ac}}{2a}$$

Roots of $$x^2−7x+12=0$$ can be calculated as,

Roots $$=\ \dfrac{-\left(-7\right)\ \pm\ \sqrt{\ \left(-7\right)^2\ -\ 4\left(1\right)\left(12\right)}}{2\left(1\right)}\ =\ \dfrac{7\ \pm\ \sqrt{\ 49\ -\ 48}}{2}\ =\ \dfrac{7\ \pm\ 1}{2}\ =\ \dfrac{7\ +\ 1}{2}\ or\ \dfrac{7\ -\ 1}{2}\ =\ 4\ or\ 3$$

So, the roots of the equation are (3, 4)

Hence, the correct answer is option A.