-6a^2+12a+18=0

Solution for -6a^2+12a+18=0 equation:

-6a^2+12a+18=0

a = -6; b = 12; c = +18;
Δ = b2-4ac
Δ = 122-4·(-6)·18
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{-(12)-24}{2*-6}=\frac{-36}{-12}
=+3
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(12)+24}{2*-6}=\frac{12}{-12}
=-1
$