Question

По математике решите пожалуйста уравнения.

Answer 1

1) Ответ: -19

$2(0.3x - 1.4) = x + 4.8 \\ 0.6x - 2.8 = x + 4.8 \\ 0.6x - x = 4.8 + 2.8 \\ - 0.4x = 7.6 \\ x = - 19$

2) Ответ: -11/14

$x - 3 \frac{1}{7} = 6x + 2 \frac{3}{14} \\ x - 6x = \frac{31}{14} + \frac{22}{7} \\ - 5x = \frac{31 + 44}{14} = \frac{55}{14} \\ x = \frac{55}{14} \div ( - 5) = \frac{55}{14} \times ( - \frac{1}{5} ) = - \frac{11}{14}$

3) Ответ: -6 39/40

$( - 2.25 - 3 \frac{2}{3} ) \times (1 \frac{2}{5} - 2.5) = ( - 2 \frac{1}{4} - 3 \frac{2}{3} ) \times (1 \frac{2}{5} - 2 \frac{1}{2} ) = ( - \frac{9}{4} - \frac{11}{2} ) \times ( \frac{7}{5} - \frac{5}{2} ) = - \frac{9 + 22}{4} \times \frac{14 - 25}{10} = - \frac{31}{4} \times ( - \frac{9}{10} ) = - \frac{279}{40} = - 6 \frac{39}{40}$

4) Ответ: -1 17/56

$(0.7 - \frac{11}{30} )( - 1 \frac{2}{7} ) - (0.25 - \frac{11}{20} )( - 2 \frac{11}{12} ) = ( \frac{7}{10} - \frac{11}{30} )( - \frac{9}{7} ) - ( \frac{1}{4} - \frac{11}{20} )( - \frac{35}{12} ) = \frac{21 - 11}{30} \times ( - \frac{9}{7} ) - \frac{5 - 11}{20} \times ( - \frac{35}{12} ) = \frac{10}{30} \times ( - \frac{9}{7} ) - ( - \frac{6}{20} ) \times ( - \frac{35}{12} ) = - \frac{3}{7} - \frac{7}{8} = - \frac{24 + 49}{56} = - \frac{73}{56} = - 1 \frac{17}{56}$