Solve for x: f(x) = 3x^{2}  x  4
Solve 
Step 

Factor out the 2 first Multiply out to verify 
Now complete the square* inside parenthesis  
To Remove 1/36 from parenthesis, Multiply it by 3.  
(x  1/6)^{2} = x^{2}  (1/3)x + 1/36  

3(1/36)  4 = 1/12  48/12 = 49/12 
Vertex (1/6, 49/12) 
Vertex is (h,k) 
This means the vertex is shifted 1/6 units right and 49/12 units up from the origin.  
*Check out completing the square for help with this step.  