f(x) is a quadratic equation with the x-side squared and a is positive which means that the graph of the function is a parabola facing up. The range of f(x) is given by {y|y ≥ k}, where k is the y-coordinate of the vertex.
[tex]f(x)=3 x^{2} +6x-8[/tex], written in vertex form is
[tex]y=3 (x+1)^{2} -11[/tex], where (h, k) = (-1, -11)
Therefore, range ={y|y ≥ -11}
