x2-4=780

Solution for x2-4=780 equation:

x2-4=780

We move all terms to the left:

x2-4-(780)=0

We add all the numbers together, and all the variables

x^2-784=0

a = 1; b = 0; c = -784;
Δ = b2-4ac
Δ = 02-4·1·(-784)
Δ = 3136
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{3136}=56$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-56}{2*1}=\frac{-56}{2}
=-28
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+56}{2*1}=\frac{56}{2}
=28
$