5x^2-20=385

Solution for 5x^2-20=385 equation:

5x^2-20=385

We move all terms to the left:

5x^2-20-(385)=0

We add all the numbers together, and all the variables

5x^2-405=0

a = 5; b = 0; c = -405;
Δ = b2-4ac
Δ = 02-4·5·(-405)
Δ = 8100
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{8100}=90$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-90}{2*5}=\frac{-90}{10}
=-9
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+90}{2*5}=\frac{90}{10}
=9
$