Решебник по математике 6 класс Мерзляк ФГОС Задание 314

\[\boxed{\mathbf{314\ (315).}\mathbf{\ }Еуроки\ - \ ДЗ\ без\ мороки}\]

\[1)\ \frac{3}{a} + \frac{9}{2a} = \frac{3 \cdot 2 + 9}{2a} = \frac{6 + 9}{2a} =\]

\[= \frac{15}{2a}\]

\[2)\ \frac{11c}{14d} + \frac{c}{21d} =\]

\[= \frac{11c \cdot 3 + c \cdot 2}{42d} = \frac{33c + 2c}{42d} =\]

\[= \frac{35c}{42d} = \frac{5c}{6d}\]

\[3)\ \frac{17p}{18q} - \frac{11p}{12q} =\]

\[= \frac{17p \cdot 2 - 11p \cdot 3}{39q} =\]

\[= \frac{34p - 33p}{39q} = \frac{p}{36q}\]

\[\boxed{\mathbf{314\ (}\mathbf{с}\mathbf{).}\mathbf{\ }Еуроки\ - \ ДЗ\ без\ мороки}\]

\[1)\ \frac{3a}{8b} - \frac{a}{5b} = \frac{3a \cdot 5 - a \cdot 8}{8 \cdot 5 \cdot b} =\]

\[= \frac{15a - 8a}{40b} = \frac{7a}{40b}\]

\[2)\ \frac{4m}{9n} + \frac{5m}{12n} =\]

\[= \frac{4m \cdot 4 + 5m \cdot 3}{36n} =\]

\[= \frac{16m + 15m}{36n} = \frac{31m}{36n}\]

\[3)\ \frac{7x}{6y} - \frac{4x}{15y} = \frac{7x \cdot 5 - 4x \cdot 2}{30y} =\]

\[= \frac{35x - 8x}{30y} = \frac{27x}{30y} = \frac{9x}{10y}\]

\[\boxed{\mathbf{314}\mathbf{.}}\]

\[15\ :38 = \frac{15}{38}\ (часть) - всех\ \]

\[роз\ составляют\ белые.\]

\[Ответ:\ \frac{15}{38}\ часть.\]