(6+x)(6+x)=361

Solution for (6+x)(6+x)=361 equation:

(6+x)(6+x)=361

We move all terms to the left:

(6+x)(6+x)-(361)=0

We add all the numbers together, and all the variables

(x+6)(x+6)-361=0

We multiply parentheses ..

(+x^2+6x+6x+36)-361=0

We get rid of parentheses

x^2+6x+6x+36-361=0

We add all the numbers together, and all the variables

x^2+12x-325=0

a = 1; b = 12; c = -325;
Δ = b2-4ac
Δ = 122-4·1·(-325)
Δ = 1444
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1444}=38$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(12)-38}{2*1}=\frac{-50}{2}
=-25
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(12)+38}{2*1}=\frac{26}{2}
=13
$