Решебник по математике 5 класс Мерзляк ФГОС Задание 751

 

\[\boxed{\mathbf{751\ (751)}.\ Еуроки\ - \ ДЗ\ без\ мороки}\]

\[1)\ \frac{52}{63} - \frac{x}{63} = \frac{25}{63}\]

\[52 - x = 25\]

\[x = 52 - 25\]

\[x = 27\]

\[Ответ:27.\]

\[2)\ \frac{x}{38} + \frac{14}{38} = \frac{23}{38}\]

\[x + 14 = 23\]

\[x = 23 - 14\]

\[x = 9\]

\[Ответ:9.\]

\[3)\ \left( \frac{12}{13} + x \right) - \frac{5}{13} = \frac{9}{13}\]

\[\frac{12}{13} + x = \frac{9}{13} + \frac{5}{13}\]

\[x = \frac{14}{13} - \frac{12}{13}\]

\[x = \frac{2}{13}\]

\[Ответ:\frac{2}{13}.\]

\[4)\ \left( x - \frac{21}{31} \right) + \frac{14}{31} = \frac{25}{31}\]

\[x - \frac{21}{31} = \frac{25}{31} - \frac{14}{31}\]

\[x = \frac{11}{31} + \frac{21}{31}\]

\[x = \frac{32}{31}\]

\[Ответ:\frac{32}{31}.\]

\[\boxed{\mathbf{751}\mathbf{\ (579)}.\ Еуроки\ - \ ДЗ\ без\ мороки}\]

\[= 30 + 14 + 30 + 30 =\]

\[= 104\ (см).\]

\[S_{1} = 12 \cdot 4 = 48\ см^{2}.\]

\[S_{3} = 12 \cdot 4 = 48\ см^{2}.\]

\[S_{2} = (18 - 4) \cdot (12 + 6 + 12) =\]

\[= 14 \cdot 30 = 420\ см^{2}.\]

\[S = S_{1} + S_{2} + S_{3} =\]

\[= 48 + 48 + 420 = 516\ см^{2}.\]

\[Ответ:104\ см;\ \ 516\ см^{2}.\]