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\Delta \mathrm{x}=\frac{2-0}{\mathrm{n}}=\frac{2}{\mathrm{n}} \cdot \mathrm{M}_{\mathrm{i}}=\frac{2}{\mathrm{n}} \mathrm{i} \text { so } \mathrm{f}\left(\mathrm{M}_{\mathrm{i}}\right)=\left\{\frac{2}{\mathrm{n}} \mathrm{i}\right\}^{2}=\frac{4}{\mathrm{n}^{2}} \mathrm{i}^{2}