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\begin{gathered} \mathrm{A}^{\prime}(\mathrm{x})=\mathrm{D}\left(\int_{0}^{\mathrm{x}} 3 \mathrm{t}^{2} \mathrm{dt}\right)=3 \mathrm{x}^{2} \cdot \mathrm{A}^{\prime}(1)=3, \mathrm{~A}^{\prime}(2)=12, \text { and } \mathrm{A}^{\prime}(3)=27 \\\end{gathered}