Краткие ответы
Задание 1:
- \(-\dfrac72\)
- \(\dfrac9{10}\)
- \(\dfrac1{25^{14}}=\dfrac1{5^{28}}\)
- \(\dfrac{64}{729}\)
Задание 2:
- \(\dfrac{75}{2}=37\dfrac12\)
- \(\dfrac{83}{4}=20\dfrac34\)
- \(\dfrac{2975}{416}=7\dfrac{63}{416}\)
- \(-\dfrac{54}{5}=-10\dfrac45\)
Задание 3:
- \(\dfrac34=0{,}75\)
- \(7\)
- \(\dfrac{16}{5}=3{,}2\)
- \(4{,}9\)
Решение
Задание 1
- Приведём дроби к знаменателю \(60\):
\[ \left(\frac1{12}-\frac{17}{15}\right)\cdot\frac{10}{3} = \left(\frac5{60}-\frac{68}{60}\right)\cdot\frac{10}{3} = -\frac{21}{20}\cdot\frac{10}{3} = -\frac72. \]
\[ \left(\frac7{15}+\frac{19}{30}\right)\cdot\frac9{11} = \left(\frac{14}{30}+\frac{19}{30}\right)\cdot\frac9{11} = \frac{33}{30}\cdot\frac9{11} = \frac9{10}. \]
\[ \left(\frac3{25}-\frac2{25}\right)^{14} = \left(\frac1{25}\right)^{14} = \frac1{25^{14}}. \]
\[ \left(\frac1{30}-\frac7{10}\right)^6 = \left(\frac1{30}-\frac{21}{30}\right)^6 = \left(-\frac23\right)^6 = \frac{64}{729}. \]
Чётная степень делает результат положительным.
Задание 2
\[ 2\frac3{17}=\frac{37}{17}=\frac{74}{34}, \]
\[ \left(2\frac3{17}+\frac1{34}\right)\cdot17 = \left(\frac{74}{34}+\frac1{34}\right)\cdot17 = \frac{75}{34}\cdot17 = \frac{75}{2}. \]
\[ \left(1\frac14-\frac3{19}\right)\cdot19 = \left(\frac54-\frac3{19}\right)\cdot19 = \frac{95}{4}-3 = \frac{83}{4}. \]
- Читаю выражение на фото как
\(\displaystyle 4\frac28\left(\frac38+1\frac4{13}\right)\):
\[ 4\frac28=\frac{17}{4},\qquad 1\frac4{13}=\frac{17}{13}. \]
\[ \frac{17}{4}\left(\frac38+\frac{17}{13}\right) = \frac{17}{4}\left(\frac{39}{104}+\frac{136}{104}\right) = \frac{17}{4}\cdot\frac{175}{104} = \frac{2975}{416}. \]
- Читаю выражение как
\(\displaystyle 5\frac25\left(\frac34-2\frac34\right)\):
\[ 5\frac25=\frac{27}{5},\qquad 2\frac34=\frac{11}{4}. \]
\[ \frac{27}{5}\left(\frac34-\frac{11}{4}\right) = \frac{27}{5}\cdot(-2) = -\frac{54}{5}. \]
Задание 3
\[ \frac{3{,}6}{5{,}9-1{,}1} = \frac{3{,}6}{4{,}8} = \frac{36}{48} = \frac34. \]
\[ \frac{1{,}3+9{,}2}{1{,}5} = \frac{10{,}5}{1{,}5} = 7. \]
\[ \frac{28}{17{,}5\cdot0{,}5} = \frac{28}{8{,}75} = 3{,}2. \]
\[ \frac{5{,}6\cdot0{,}7}{0{,}8} = \frac{3{,}92}{0{,}8} = 4{,}9. \]
Проверка, например:
\[ 4{,}8\cdot0{,}75=3{,}6,\qquad 1{,}5\cdot7=10{,}5. \]
