What is the x-coordinate of the vertex of the function f x 3x2 12x 5?

To find the x-coordinate of the vertex of the quadratic function ( f(x) = 3x^2 + 12x + 5 ), you can use the formula ( x = -\frac{b}{2a} ), where ( a = 3 ) and ( b = 12 ). Substituting these values in gives ( x = -\frac{12}{2(3)} = -\frac{12}{6} = -2 ). Therefore, the x-coordinate of the vertex is ( -2 ).