r^2=900

Solution for r^2=900 equation:

r^2=900

We move all terms to the left:

r^2-(900)=0

a = 1; b = 0; c = -900;
Δ = b2-4ac
Δ = 02-4·1·(-900)
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*1}=\frac{-60}{2}
=-30
$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+60}{2*1}=\frac{60}{2}
=30
$