(x+9)(x+9)=169

Solution for (x+9)(x+9)=169 equation:

(x+9)(x+9)=169

We move all terms to the left:

(x+9)(x+9)-(169)=0

We multiply parentheses ..

(+x^2+9x+9x+81)-169=0

We get rid of parentheses

x^2+9x+9x+81-169=0

We add all the numbers together, and all the variables

x^2+18x-88=0

a = 1; b = 18; c = -88;
Δ = b2-4ac
Δ = 182-4·1·(-88)
Δ = 676
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{676}=26$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(18)-26}{2*1}=\frac{-44}{2}
=-22
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(18)+26}{2*1}=\frac{8}{2}
=4
$