a^2=20.25

Solution for a^2=20.25 equation:

a^2=20.25

We move all terms to the left:

a^2-(20.25)=0

We add all the numbers together, and all the variables

a^2-20.25=0

a = 1; b = 0; c = -20.25;
Δ = b2-4ac
Δ = 02-4·1·(-20.25)
Δ = 81
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{81}=9$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-9}{2*1}=\frac{-9}{2}
=-4+1/2
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+9}{2*1}=\frac{9}{2}
=4+1/2
$