90^2+90^2=x^2

Solution for 90^2+90^2=x^2 equation:

90^2+90^2=x^2

We move all terms to the left:

90^2+90^2-(x^2)=0

We add all the numbers together, and all the variables

-1x^2+16200=0

a = -1; b = 0; c = +16200;
Δ = b2-4ac
Δ = 02-4·(-1)·16200
Δ = 64800
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:

$\sqrt{\Delta}=\sqrt{64800}=\sqrt{32400*2}=\sqrt{32400}*\sqrt{2}=180\sqrt{2}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-180\sqrt{2}}{2*-1}=\frac{0-180\sqrt{2}}{-2}
=-\frac{180\sqrt{2}}{-2}
=-\frac{90\sqrt{2}}{-1}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+180\sqrt{2}}{2*-1}=\frac{0+180\sqrt{2}}{-2}
=\frac{180\sqrt{2}}{-2}
=\frac{90\sqrt{2}}{-1}
$