Відповідь:

[tex]1) \frac{5}{42(x-y)}[/tex]

[tex]2) \frac{-2y^2-4y+13}{(y-3)(y+3)}[/tex]

Пояснення:

[tex]1) \frac{3}{14x-14y} -\frac{2}{21x-21y} =\frac{3}{14(x-y)} -\frac{2}{21(x-y)}=\frac{9-4}{2 \cdot 3 \cdot 7(x-y)} =\frac{5}{42(x-y)}[/tex]

[tex]2) \frac{2-3y}{y^2-9} +\frac{5-2y}{y-3} =\frac{2-3y}{(y-3)(y+3)} +\frac{5-2y}{y-3} =\frac{2-3y+(5-2y)(y+3)}{(y-3)(y+3)} =\frac{2-3y+5y+15-2y^2-6y}{(y-3)(y+3)} =\\=\frac{-2y^2-4y+13}{(y-3)(y+3)}[/tex]