36a^2+9=90

Solution for 36a^2+9=90 equation:

36a^2+9=90

We move all terms to the left:

36a^2+9-(90)=0

We add all the numbers together, and all the variables

36a^2-81=0

a = 36; b = 0; c = -81;
Δ = b2-4ac
Δ = 02-4·36·(-81)
Δ = 11664
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{11664}=108$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-108}{2*36}=\frac{-108}{72}
=-1+1/2
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+108}{2*36}=\frac{108}{72}
=1+1/2
$