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.
\(f(x)=3 x^{2} +6x-8\), written in vertex form is
\(y=3 (x+1)^{2} -11\), where (h, k) = (-1, -11)
Therefore, range ={y|y ≥ -11}
