a) exponential smoothing: \( \mathrm{Ft}+1=\alpha \mathrm{At}+(1-\alpha) \mathrm{Ft} \) for \( \alpha=0.2,1-\alpha=0.8 \) \[ \begin{array}{l} \mathrm{F} 2=\alpha \mathrm{A} 1+(1-\alpha) \mat