x^2-76=400

Solution for x^2-76=400 equation:

x^2-76=400

We move all terms to the left:

x^2-76-(400)=0

We add all the numbers together, and all the variables

x^2-476=0

a = 1; b = 0; c = -476;
Δ = b2-4ac
Δ = 02-4·1·(-476)
Δ = 1904
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:

$\sqrt{\Delta}=\sqrt{1904}=\sqrt{16*119}=\sqrt{16}*\sqrt{119}=4\sqrt{119}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-4\sqrt{119}}{2*1}=\frac{0-4\sqrt{119}}{2}
=-\frac{4\sqrt{119}}{2}
=-2\sqrt{119}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+4\sqrt{119}}{2*1}=\frac{0+4\sqrt{119}}{2}
=\frac{4\sqrt{119}}{2}
=2\sqrt{119}
$