-x(x+2)-6=-23

Solution for -x(x+2)-6=-23 equation:

-x(x+2)-6=-23

We move all terms to the left:

-x(x+2)-6-(-23)=0

We add all the numbers together, and all the variables

-x(x+2)+17=0

We multiply parentheses

-x^2-2x+17=0

We add all the numbers together, and all the variables

-1x^2-2x+17=0

a = -1; b = -2; c = +17;
Δ = b2-4ac
Δ = -22-4·(-1)·17
Δ = 72
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:

$\sqrt{\Delta}=\sqrt{72}=\sqrt{36*2}=\sqrt{36}*\sqrt{2}=6\sqrt{2}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-2)-6\sqrt{2}}{2*-1}=\frac{2-6\sqrt{2}}{-2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-2)+6\sqrt{2}}{2*-1}=\frac{2+6\sqrt{2}}{-2}
$