20=5x2+5

Solution for 20=5x2+5 equation:

20=5x^2+5

We move all terms to the left:

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

We get rid of parentheses

-5x^2-5+20=0

We add all the numbers together, and all the variables

-5x^2+15=0

a = -5; b = 0; c = +15;
Δ = b2-4ac
Δ = 02-4·(-5)·15
Δ = 300
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:

$\sqrt{\Delta}=\sqrt{300}=\sqrt{100*3}=\sqrt{100}*\sqrt{3}=10\sqrt{3}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-10\sqrt{3}}{2*-5}=\frac{0-10\sqrt{3}}{-10}
=-\frac{10\sqrt{3}}{-10}
=-\frac{\sqrt{3}}{-1}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+10\sqrt{3}}{2*-5}=\frac{0+10\sqrt{3}}{-10}
=\frac{10\sqrt{3}}{-10}
=\frac{\sqrt{3}}{-1}
$