28. For each of the following functions, determine all of its stationary points (within the given domain). Then classify each stationary point as either a local maximum, a local minimum or a saddle point. g_{1}: \mathbf{R} \rightarrow \mathbf{R}, g_{1}(x)=x\left(2 x^{2}-9 x+12\right) g_{2}:(-2,2) \rightarrow \mathbf{R}, g_{2}(x)=\cos \left(\pi x^{2}\right)

Fig: 1

Fig: 2

Fig: 3