4.257 Вычислите: a) -4 - (-2); б) 5-6; в) -2+; г) -0,9; д) --(-0,6); e) -5,1-3; ж) 12,5 - 7; 3)-3-(-4,2).

Ответ:

а) \[ -4\frac{1}{3} - \left(-2\frac{7}{9}\right) = -4\frac{1}{3} + 2\frac{7}{9} = -4\frac{3}{9} + 2\frac{7}{9} = -1\frac{5}{9} \]

б) \[ 5\frac{2}{7} - 6\frac{5}{14} = 5\frac{4}{14} - 6\frac{5}{14} = -1\frac{1}{14} \]

в) \[ -2\frac{3}{16} + \frac{5}{8} = -2\frac{3}{16} + \frac{10}{16} = -2 + \frac{7}{16} = -1\frac{9}{16} \]

г) \[ \frac{3}{5} - 0,9 = \frac{3}{5} - \frac{9}{10} = \frac{6}{10} - \frac{9}{10} = -\frac{3}{10} = -0,3 \]

д) \[ -\frac{17}{30} - (-0,6) = -\frac{17}{30} + \frac{6}{10} = -\frac{17}{30} + \frac{18}{30} = \frac{1}{30} \]

е) \[ -5,1 - 3\frac{1}{7} = -5\frac{1}{10} - 3\frac{1}{7} = -5\frac{7}{70} - 3\frac{10}{70} = -8\frac{17}{70} \]

ж) \[ 12,5 - 7\frac{3}{4} = 12\frac{5}{10} - 7\frac{3}{4} = 12\frac{10}{20} - 7\frac{15}{20} = 4\frac{15}{20} = 4\frac{3}{4} \]

з) \[ -3\frac{1}{7} - (-4,2) = -3\frac{1}{7} + 4,2 = -3\frac{1}{7} + 4\frac{2}{10} = -3\frac{10}{70} + 4\frac{14}{70} = 1\frac{4}{70} = 1\frac{2}{35} \]

Ответ: a) \[-1\frac{5}{9}\]; б) \[-1\frac{1}{14}\]; в) \[-1\frac{9}{16}\]; г) -0,3; д) \(\frac{1}{30}\); e) \[-8\frac{17}{70}\]; ж) \[4\frac{3}{4}\]; з) \[1\frac{2}{35}\]