Step 1. Calculate the discriminant:
[tex] \Delta = b^2 - 4ac[/tex]
Step 2.
If [tex]\Delta>0[/tex], there are two solutions, both real numbers
If [tex]\Delta=0[/tex], there is only one solution, real number
If [tex]\Delta<0[/tex], there are two solutions, both complex numbers
In your case:
a=3, b=6, c=4
[tex] \Delta = 6^2 - 4 \cdot 3 \cdot 4 = -12[/tex]
So you have two solutions, both complex numbers