Question 664215
{{{-4x^2-9x-6=0}}}

Divide by -1

{{{4x^2+9x+6=0}}}

factorize by completing the squares method

{{{4x^2+9x=-6}}}

add (81/4) on both sides

{{{4x^2+9x+(81/4) = -6-(81/4)}}}


{{{(2x+(9/2))^2=-105/4}}}

take the square root 
2x+(9/2) = +/- sqrt(-105/4)


2x= -(9/2) +/- sqrt(105)*i/2

x= (-9/4) +/- sqrt(105)*i/4