Ответ:

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[tex]\displaystyle\bf\\\frac{k^{2} -4}{k+1} -\frac{2k-5}{k+1} +\frac{3k-k^{2} }{k+1} =\frac{k^{2} -4-2k+5+3k-k^{2} }{k+1} =\\\\\\=\frac{(k^{2} - k^{2})+(3k-2k) +(5-4)}{k+1} =\frac{k+1}{k+1} =1\\\\\\1=1 \ - \ verno[/tex]