Question

срочно! плиз сделайте дз по матем​

Answer 1

1. а)

$\frac{1}{4} + 2.7 = 0.25 + 2.7 = 2.95$

б)

$2 \frac{1}{7} \times 0.7 = \frac{9}{7} \times \frac{7}{10} = \frac{9}{10} = 0.9$

в)

$4.5 \div 2 \frac{1}{2} = \frac{45}{10} \div \frac{5}{2} = \frac{45}{10} \times \frac{2}{5} = \frac{9}{5} = 1.8$

г)

$3 \frac{2}{3} - 0.25 = \frac{11}{3} - \frac{25}{100} = \frac{11}{ 3} - \frac{1}{4} = \frac{44 - 3}{12} = \frac{41}{12} = 3 \frac{5}{12}$

2.

$4.5 \times \frac{2}{3} - 1 \frac{5}{7} \div 1.2 + 3 \frac{1}{5} \times 3 \frac{1}{8} = 11 \frac{4}{7}$

$1. \: \: 4.5 \times \frac{2}{3} = \frac{45}{10} \times \frac{2}{3} = \frac{15}{5} = 3$

$2. \: \: 1 \frac{5}{7} \div 1.2 = \frac{12}{7} \times \frac{10}{12} = \frac{10}{7}$

$3. \: \: 3 \frac{1}{5} \times 3 \frac{1 }{8} = \frac{16}{5} \times \frac{25}{8} = 2 \times 5 = 10$

$4. \: \: 3 - \frac{10}{7} = 2 \frac{7}{7} - 1 \frac{3}{7} = 1 \frac{7 - 3}{7} = 1 \frac{4}{7}$

$5. \: \: 1 \frac{4}{7} + 10 = 11 \frac{4}{7}$

3.

$\frac{(3 \frac{1}{3} - 2.5) \times 6.6}{15.717 \div 3.1 - \frac{1}{7} \times 0.49 } = \frac{( \frac{10}{3} - \frac{5}{2} ) \times 6.6 }{5.07 - 0.07} = \frac{( \frac{20 - 15}{6}) \times 6.6}{5} = \frac{ \frac{5}{6} \times 6.6}{5} = \frac{5 \times 1.1}{5} = 1.1$

4.

$3 \frac{1}{3} \div 2.4 + 9.888 - ( \frac{1}{18} + 7.888) = \frac{10}{3} \times \frac{10}{24} + 9.888 - \frac{1}{18} - 7.888 = \frac{25}{18} - \frac{1}{18} + (9.888 - 7.888) = \frac{24}{18} - 2 = \frac{4}{3} - 2 = \frac{4}{3} - 1 \frac{3}{3} = \frac{4}{3} - \frac{6}{3} = - \frac{2}{3}$