18^2+18^2=x^2

Solution for 18^2+18^2=x^2 equation:

18^2+18^2=x^2

We move all terms to the left:

18^2+18^2-(x^2)=0

We add all the numbers together, and all the variables

-1x^2+648=0

a = -1; b = 0; c = +648;
Δ = b2-4ac
Δ = 02-4·(-1)·648
Δ = 2592
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:

$\sqrt{\Delta}=\sqrt{2592}=\sqrt{1296*2}=\sqrt{1296}*\sqrt{2}=36\sqrt{2}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-36\sqrt{2}}{2*-1}=\frac{0-36\sqrt{2}}{-2}
=-\frac{36\sqrt{2}}{-2}
=-\frac{18\sqrt{2}}{-1}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+36\sqrt{2}}{2*-1}=\frac{0+36\sqrt{2}}{-2}
=\frac{36\sqrt{2}}{-2}
=\frac{18\sqrt{2}}{-1}
$