300=3r^2

Solution for 300=3r^2 equation:

300=3r^2

We move all terms to the left:

300-(3r^2)=0

a = -3; b = 0; c = +300;
Δ = b2-4ac
Δ = 02-4·(-3)·300
Δ = 3600
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{3600}=60$
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-60}{2*-3}=\frac{-60}{-6}
=+10
$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+60}{2*-3}=\frac{60}{-6}
=-10
$