12.96=r^2

Solution for 12.96=r^2 equation:

12.96=r^2

We move all terms to the left:

12.96-(r^2)=0

We add all the numbers together, and all the variables

-1r^2+12.96=0

a = -1; b = 0; c = +12.96;
Δ = b2-4ac
Δ = 02-4·(-1)·12.96
Δ = 51.84
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{51.84}}{2*-1}=\frac{0-\sqrt{51.84}}{-2}
=-\frac{\sqrt{}}{-2}
$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+\sqrt{51.84}}{2*-1}=\frac{0+\sqrt{51.84}}{-2}
=\frac{\sqrt{}}{-2}
$