A function \(f(x)\) is such that

\(f(x)=e^{3x}-4,\)

for \(x\in\mathbb R\).

(a) Find the range of \(f\).

(b) Find an expression for \(f^{-1}(x)\).

(c) On the axes, sketch the graphs of \(y=f(x)\) and \(y=f^{-1}(x)\), stating the exact values of the intercepts with the coordinate axes.