1. Представьте в виде дроби выражение: 1) 5b/28 + 9b/28; 2) 9m/7n − 2m/7n; 3) (5x − 3y)/8z + (3x − 13y)/8z; 4) (4c − 3d)/cd − (c − 3d)/cd; 5) 6x/(x² − 16) − 24/(x² − 16).

1) \(\dfrac{5b}{28}+\dfrac{9b}{28}=\dfrac{14b}{28}=\dfrac{b}{2}\).

2) \(\dfrac{9m}{7n}-\dfrac{2m}{7n}=\dfrac{7m}{7n}=\dfrac{m}{n}\).

3) \(\dfrac{5x-3y}{8z}+\dfrac{3x-13y}{8z}=\dfrac{8x-16y}{8z}=\dfrac{x-2y}{z}\).

4) \(\dfrac{4c-3d}{cd}-\dfrac{c-3d}{cd}=\dfrac{3c}{cd}=\dfrac{3}{d}\).

5) \(\dfrac{6x}{x^2-16}-\dfrac{24}{x^2-16}=\dfrac{6x-24}{x^2-16}=\dfrac{6(x-4)}{(x-4)(x+4)}=\dfrac{6}{x+4}\).

Ограничения: \(n\ne0\), \(z\ne0\), \(c\ne0\), \(d\ne0\), \(x\ne-4\), \(x\ne4\).

Ответ: 1) \(\dfrac{b}{2}\); 2) \(\dfrac{m}{n}\); 3) \(\dfrac{x-2y}{z}\); 4) \(\dfrac{3}{d}\); 5) \(\dfrac{6}{x+4}\).