256=25+x^2

Solution for 256=25+x^2 equation:

256=25+x^2

We move all terms to the left:

256-(25+x^2)=0

We get rid of parentheses

-x^2-25+256=0

We add all the numbers together, and all the variables

-1x^2+231=0

a = -1; b = 0; c = +231;
Δ = b2-4ac
Δ = 02-4·(-1)·231
Δ = 924
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:

$\sqrt{\Delta}=\sqrt{924}=\sqrt{4*231}=\sqrt{4}*\sqrt{231}=2\sqrt{231}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-2\sqrt{231}}{2*-1}=\frac{0-2\sqrt{231}}{-2}
=-\frac{2\sqrt{231}}{-2}
=-\frac{\sqrt{231}}{-1}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+2\sqrt{231}}{2*-1}=\frac{0+2\sqrt{231}}{-2}
=\frac{2\sqrt{231}}{-2}
=\frac{\sqrt{231}}{-1}
$