69. Представьте в виде дроби выражение: 1) 7k/(18p) − 4k/(18p); 2) (a − b)/(2b) − a/(2b); 3) −(a − 12b)/(27a) + (a + 15b)/(27a); 4) (x − 7y)/(xy) − (x − 4y)/(xy); 5) (10a + 6b)/(11a³) − (6b − a)/(11a³); 6) (x² − xy)/(x²y) + (2xy − 3x²)/(x²y).

Question

Вопрос:

Accepted Answer

\(\frac{7k}{18p}-\frac{4k}{18p}=\frac{7k-4k}{18p}=\frac{3k}{18p}=\frac{k}{6p}\).
\(\frac{a-b}{2b}-\frac{a}{2b}=\frac{a-b-a}{2b}=-\frac{b}{2b}=-\frac12\).
\(-\frac{a-12b}{27a}+\frac{a+15b}{27a}=\frac{-a+12b+a+15b}{27a}=\frac{27b}{27a}=\frac{b}{a}\).
\(\frac{x-7y}{xy}-\frac{x-4y}{xy}=\frac{x-7y-x+4y}{xy}=\frac{-3y}{xy}=-\frac{3}{x}\).
\(\frac{10a+6b}{11a^3}-\frac{6b-a}{11a^3}=\frac{10a+6b-6b+a}{11a^3}=\frac{11a}{11a^3}=\frac{1}{a^2}\).
\(\frac{x^2-xy}{x^2y}+\frac{2xy-3x^2}{x^2y}=\frac{x^2-xy+2xy-3x^2}{x^2y}=\frac{-2x^2+xy}{x^2y}=\frac{y-2x}{xy}\).

Ответ: 1) \(\frac{k}{6p}\); 2) \(-\frac12\); 3) \(\frac{b}{a}\); 4) \(-\frac3x\); 5) \(\frac{1}{a^2}\); 6) \(\frac{y-2x}{xy}\).