36=4a^2

Solution for 36=4a^2 equation:

36=4a^2

We move all terms to the left:

36-(4a^2)=0

a = -4; b = 0; c = +36;
Δ = b2-4ac
Δ = 02-4·(-4)·36
Δ = 576
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{576}=24$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-24}{2*-4}=\frac{-24}{-8}
=+3
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+24}{2*-4}=\frac{24}{-8}
=-3
$