Подайте у вигляді дробу вираз: 1) $$\frac{7k}{18p} - \frac{4k}{18p}$$; 2) $$\frac{a-b}{2b} - \frac{a}{2b}$$; 3) $$\frac{a-12b}{27a} + \frac{a+15b}{27a}$$; 4) $$\frac{x-7y}{xy} - \frac{x-4y}{xy}$$; 5) $$\frac{10a+6b}{11a^3} - \frac{6b-a}{11a^3}$$; 6) $$\frac{x^2-xy}{x^2y} + \frac{2xy-3x^2}{x^2y}$$.

Обчислимо вирази, звівши дроби до спільного знаменника:

1. $$\frac{7k}{18p} - \frac{4k}{18p} = \frac{7k - 4k}{18p} = \frac{3k}{18p} = \frac{k}{6p}$$
2. $$\frac{a-b}{2b} - \frac{a}{2b} = \frac{a - b - a}{2b} = \frac{-b}{2b} = -\frac{1}{2}$$
3. $$\frac{a-12b}{27a} + \frac{a+15b}{27a} = \frac{a - 12b + a + 15b}{27a} = \frac{2a + 3b}{27a}$$
4. $$\frac{x-7y}{xy} - \frac{x-4y}{xy} = \frac{x - 7y - (x - 4y)}{xy} = \frac{x - 7y - x + 4y}{xy} = \frac{-3y}{xy} = -\frac{3}{x}$$
5. $$\frac{10a+6b}{11a^3} - \frac{6b-a}{11a^3} = \frac{10a + 6b - (6b - a)}{11a^3} = \frac{10a + 6b - 6b + a}{11a^3} = \frac{11a}{11a^3} = \frac{1}{a^2}$$
6. $$\frac{x^2-xy}{x^2y} + \frac{2xy-3x^2}{x^2y} = \frac{x^2 - xy + 2xy - 3x^2}{x^2y} = \frac{-2x^2 + xy}{x^2y} = \frac{x(-2x + y)}{x^2y} = \frac{y - 2x}{xy}$$