Find the focus of the parabola: .
We must get the equation into the form: .
Then the vertex is at and is the directed distance from the vertex to the focus.
We have: .
Divide by 3: .
Complete the square: .
. . And we have: .
The vertex is: . . . . and the parabola opens downward.
Since . . . The focus is unit below the vertex.
Therefore, the focus is: .