x(x-12)=805

Solution for x(x-12)=805 equation:

x(x-12)=805

We move all terms to the left:

x(x-12)-(805)=0

We multiply parentheses

x^2-12x-805=0

a = 1; b = -12; c = -805;
Δ = b2-4ac
Δ = -122-4·1·(-805)
Δ = 3364
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{3364}=58$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-12)-58}{2*1}=\frac{-46}{2}
=-23
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-12)+58}{2*1}=\frac{70}{2}
=35
$