a2+18a-66=-3

Solution for a2+18a-66=-3 equation:

a2+18a-66=-3

We move all terms to the left:

a2+18a-66-(-3)=0

We add all the numbers together, and all the variables

a^2+18a-63=0

a = 1; b = 18; c = -63;
Δ = b2-4ac
Δ = 182-4·1·(-63)
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{-(18)-24}{2*1}=\frac{-42}{2}
=-21
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(18)+24}{2*1}=\frac{6}{2}
=3
$