336=x^2-9x

Solution for 336=x^2-9x equation:

336=x^2-9x

We move all terms to the left:

336-(x^2-9x)=0

We get rid of parentheses

-x^2+9x+336=0

We add all the numbers together, and all the variables

-1x^2+9x+336=0

a = -1; b = 9; c = +336;
Δ = b2-4ac
Δ = 92-4·(-1)·336
Δ = 1425
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{1425}=\sqrt{25*57}=\sqrt{25}*\sqrt{57}=5\sqrt{57}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(9)-5\sqrt{57}}{2*-1}=\frac{-9-5\sqrt{57}}{-2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(9)+5\sqrt{57}}{2*-1}=\frac{-9+5\sqrt{57}}{-2}
$