128=x*x

Solution for 128=x*x equation:

128=x*x

We move all terms to the left:

128-(x*x)=0

We add all the numbers together, and all the variables

-(+x*x)+128=0

We get rid of parentheses

-x*x+128=0

Wy multiply elements

-1x^2+128=0

a = -1; b = 0; c = +128;
Δ = b2-4ac
Δ = 02-4·(-1)·128
Δ = 512
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:

$\sqrt{\Delta}=\sqrt{512}=\sqrt{256*2}=\sqrt{256}*\sqrt{2}=16\sqrt{2}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-16\sqrt{2}}{2*-1}=\frac{0-16\sqrt{2}}{-2}
=-\frac{16\sqrt{2}}{-2}
=-\frac{8\sqrt{2}}{-1}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+16\sqrt{2}}{2*-1}=\frac{0+16\sqrt{2}}{-2}
=\frac{16\sqrt{2}}{-2}
=\frac{8\sqrt{2}}{-1}
$