20.3=r^2

Solution for 20.3=r^2 equation:

20.3=r^2

We move all terms to the left:

20.3-(r^2)=0

We add all the numbers together, and all the variables

-1r^2+20.3=0

a = -1; b = 0; c = +20.3;
Δ = b2-4ac
Δ = 02-4·(-1)·20.3
Δ = 81.2
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-\sqrt{81.2}}{2*-1}=\frac{0-\sqrt{81.2}}{-2}
=-\frac{\sqrt{}}{-2}
$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+\sqrt{81.2}}{2*-1}=\frac{0+\sqrt{81.2}}{-2}
=\frac{\sqrt{}}{-2}
$