a2=2.25

Solution for a2=2.25 equation:

a2=2.25

We move all terms to the left:

a2-(2.25)=0

We add all the numbers together, and all the variables

a^2-2.25=0

a = 1; b = 0; c = -2.25;
Δ = b2-4ac
Δ = 02-4·1·(-2.25)
Δ = 9
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{9}=3$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-3}{2*1}=\frac{-3}{2}
=-1+1/2
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+3}{2*1}=\frac{3}{2}
=1+1/2
$