20x^2-405=0

Solution for 20x^2-405=0 equation:

20x^2-405=0

a = 20; b = 0; c = -405;
Δ = b2-4ac
Δ = 02-4·20·(-405)
Δ = 32400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{32400}=180$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-180}{2*20}=\frac{-180}{40}
=-4+1/2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+180}{2*20}=\frac{180}{40}
=4+1/2
$