(a) Find the coordinates of the stationary points on the curve \(y=(2 x+1)^{2}(x-3)\). (b) On the axes, sketch the graph of \(y=(2 x+1)^{2}(x-3)\), stating the intercepts with the axes. (c) Write down the values of \(k\) for which the equation \((2 x+1)^{2}(x-3)=k\) has exactly one solution.