№ 4.4 Алгебра = № 4.4 Математика
Подайте у вигляді дробу:
1) $\frac{3}{5a}\ -\ \frac{1}{2a};$
2) $\frac{a}{4b}\ +\ \frac{7a}{5b};$
3) $\frac{2a^2}{9b}\ +\ \frac{5a^2}{18b};$
4) $\frac{7m}{12n^2}\ -\ \frac{m}{18n^2}.$
Розв'язок:
1) $\frac{3}{5a}\ -\ \frac{1}{2a}\ =\ \frac{6\ -\ 5\ }{10a}\ =\ \frac{1\ }{10a};$
2) $\frac{a}{4b}\ +\ \frac{7a}{5b}\ =\ \frac{5a\ +\ 28a}{20b}\ =\ \frac{33a}{20b};$
3) $\frac{2a^2}{9b}\ +\ \frac{5a^2}{18b}\ =\ \frac{4a^2\ +\ 5a^2}{18b}\ =$
$= \frac{9a^2}{18b}\ =\ \frac{a^2}{2b};$
4) $\frac{7m}{12n^2}\ -\ \frac{m}{18n^2}\ =\ \frac{21m\ -\ 2m\ }{36n^2}\ =$
$= \frac{19m\ }{36n^2}.$