Question

Срочно!!!
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Answer 1

$OTBET: \boxed {0,2}.$

Пошаговое объяснение:

$\displaystyle\\\frac{s-f}{f^2+s^2}*(\frac{f+s}{f} -\frac{2f}{f-s} )\\\\1.\\\\\frac{f+s}{f}-\frac{2f}{f-s} =\frac{(f+s)*(f-s)-2f*f}{f*(f-s)}=\frac{f^2-s^2-2f^2}{f*(f-s)}=\\\\=\frac{-s^2-f^2}{f*(f-s)}=-\frac{s^2+f^2}{f*(f-s)} =-\frac{f^2+s^2}{f*(f-s)}=\frac{f^2+s^2}{f*(s-f)} .\\\\ 2.\\\\\frac{s-f}{f^2+s^2} *\frac{f^2+s^2}{f*(s-f)} =\frac{1}{f}.\\\\3.\\\\f=5\ \ \ \ \ \ \Rightarrow\\\\\frac{1}{f}=\frac{1}{5}=0,2.$