16+x*x=400

Solution for 16+x*x=400 equation:

16+x*x=400

We move all terms to the left:

16+x*x-(400)=0

We add all the numbers together, and all the variables

x*x-384=0

Wy multiply elements

x^2-384=0

a = 1; b = 0; c = -384;
Δ = b2-4ac
Δ = 02-4·1·(-384)
Δ = 1536
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:

$\sqrt{\Delta}=\sqrt{1536}=\sqrt{256*6}=\sqrt{256}*\sqrt{6}=16\sqrt{6}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-16\sqrt{6}}{2*1}=\frac{0-16\sqrt{6}}{2}
=-\frac{16\sqrt{6}}{2}
=-8\sqrt{6}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+16\sqrt{6}}{2*1}=\frac{0+16\sqrt{6}}{2}
=\frac{16\sqrt{6}}{2}
=8\sqrt{6}
$