This quadratic does not have any real roots.
It is a parabola that opens downward with vertex at (11/24, -.48) which means the vertex is below the x-axis and therefore will not have any real roots.
Imaginary roots would be
x = [11 +- sqrt (121 - 4(-12)(-3)] / (-24)
x = [11 + - i sqrt(23) ] / (-24)
