5+36b^2=21

Solution for 5+36b^2=21 equation:

5+36b^2=21

We move all terms to the left:

5+36b^2-(21)=0

We add all the numbers together, and all the variables

36b^2-16=0

a = 36; b = 0; c = -16;
Δ = b2-4ac
Δ = 02-4·36·(-16)
Δ = 2304
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2304}=48$
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-48}{2*36}=\frac{-48}{72}
=-2/3
$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+48}{2*36}=\frac{48}{72}
=2/3
$