(x+6)-x(x+6)=0

Solution for (x+6)-x(x+6)=0 equation:

(x+6)-x(x+6)=0

We multiply parentheses

-x^2+(x+6)-6x=0

We get rid of parentheses

-x^2+x-6x+6=0

We add all the numbers together, and all the variables

-1x^2-5x+6=0

a = -1; b = -5; c = +6;
Δ = b2-4ac
Δ = -52-4·(-1)·6
Δ = 49
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{49}=7$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-5)-7}{2*-1}=\frac{-2}{-2}
=1
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-5)+7}{2*-1}=\frac{12}{-2}
=-6
$