3.° Выполните вычитание: 3) m²/m²-9 - m/m+3;

3) $$\frac{m^2}{m^2 - 9} - \frac{m}{m+3} = \frac{m^2}{(m-3)(m+3)} - \frac{m(m-3)}{(m+3)(m-3)} = \frac{m^2 - m^2 + 3m}{(m-3)(m+3)} = \frac{3m}{(m-3)(m+3)} = \frac{3m}{m^2 - 9}$$

Ответ: $$\frac{3m}{m^2 - 9}$$