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\operatorname{At}(-1,1), \mathrm{m}_{\tan }=\lim\limits_{h \rightarrow 0} \frac{f(-1+h)-f(-1)}{(-1+h)-(-1)}=\lim\limits_{h \rightarrow 0} \frac{\left\{1-2 h+h^{2}\right\}-1}{h}=\lim\limits_{h \rightarrow 0} \frac{-2 h+h^{2}}{h}=-\mathbf{2}