-x2-9x+252=0

Solution for -x2-9x+252=0 equation:

-x2-9x+252=0

We add all the numbers together, and all the variables

-1x^2-9x+252=0

a = -1; b = -9; c = +252;
Δ = b2-4ac
Δ = -92-4·(-1)·252
Δ = 1089
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1089}=33$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-9)-33}{2*-1}=\frac{-24}{-2}
=+12
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-9)+33}{2*-1}=\frac{42}{-2}
=-21
$