(x+-6)(x+-6)=26

Solution for (x+-6)(x+-6)=26 equation:

(x+-6)(x+-6)=26

We move all terms to the left:

(x+-6)(x+-6)-(26)=0

We add all the numbers together, and all the variables

(x-6)(x-6)-26=0

We multiply parentheses ..

(+x^2-6x-6x+36)-26=0

We get rid of parentheses

x^2-6x-6x+36-26=0

We add all the numbers together, and all the variables

x^2-12x+10=0

a = 1; b = -12; c = +10;
Δ = b2-4ac
Δ = -122-4·1·10
Δ = 104
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:

$\sqrt{\Delta}=\sqrt{104}=\sqrt{4*26}=\sqrt{4}*\sqrt{26}=2\sqrt{26}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-12)-2\sqrt{26}}{2*1}=\frac{12-2\sqrt{26}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-12)+2\sqrt{26}}{2*1}=\frac{12+2\sqrt{26}}{2}
$