1 вариант 1. Вычислить: 1. 3⋅5/18 2. 42⋅7/18 3. 49/15⋅18/9 4. 36/35

Ответ: 1) 5/6; 2) 49/3; 3) 168/25

Решение:

1. 3 \(\cdot\) \(\frac{5}{18}\) = \(\frac{3}{1}\) \(\cdot\) \(\frac{5}{18}\) = \(\frac{3 \cdot 5}{1 \cdot 18}\) = \(\frac{15}{18}\) = \(\frac{5}{6}\)

2. 42 \(\cdot\) \(\frac{7}{18}\) = \(\frac{42}{1}\) \(\cdot\) \(\frac{7}{18}\) = \(\frac{42 \cdot 7}{1 \cdot 18}\) = \(\frac{294}{18}\) = \(\frac{49}{3}\)

3. \(\frac{49}{15}\) \(\cdot\) \(\frac{18}{9}\) = \(\frac{49 \cdot 18}{15 \cdot 9}\) = \(\frac{49 \cdot 2}{5 \cdot 1}\) = \(\frac{98}{5}\) = 19\(\frac{3}{5}\) = \(\frac{168}{25}\)

4. \(\frac{36}{35}\) - тут нечего считать

Ответ: 1) 5/6; 2) 49/3; 3) 168/25