18^2=a^2+a^2

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

18^2=a^2+a^2

We move all terms to the left:

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

We add all the numbers together, and all the variables

-(a^2+a^2)+324=0

We get rid of parentheses

-a^2-a^2+324=0

We add all the numbers together, and all the variables

-2a^2+324=0

a = -2; b = 0; c = +324;
Δ = b2-4ac
Δ = 02-4·(-2)·324
Δ = 2592
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{2592}=\sqrt{1296*2}=\sqrt{1296}*\sqrt{2}=36\sqrt{2}$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-36\sqrt{2}}{2*-2}=\frac{0-36\sqrt{2}}{-4}
=-\frac{36\sqrt{2}}{-4}
=-\frac{9\sqrt{2}}{-1}
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+36\sqrt{2}}{2*-2}=\frac{0+36\sqrt{2}}{-4}
=\frac{36\sqrt{2}}{-4}
=\frac{9\sqrt{2}}{-1}
$