Ответ:

  1. \(m^2-16=(m-4)(m+4)\).
    \[\frac{4}{(m-4)(m+4)}+\frac{3(m-4)}{(m-4)(m+4)}=\frac{3m-8}{m^2-16}.\]
    Ограничения: \(m\ne\pm4\).
  2. \(y^2-25=(y-5)(y+5)\).
    \[\frac{y+2}{(y-5)(y+5)}+\frac{3(y+5)}{(y-5)(y+5)}=\frac{4y+17}{y^2-25}.\]
    Ограничения: \(y\ne\pm5\).
  3. \(c^2-d^2=(c-d)(c+d)\).
    \[\frac{c}{(c-d)(c+d)}+\frac{c-d}{(c-d)(c+d)}=\frac{2c-d}{c^2-d^2}.\]
    Ограничения: \(c\ne d\), \(c\ne-d\).