Математика: а) в обыкновенных б) в десятичных

а) в обыкновенных
б) в десятичных

Ответы

kopulenkodimasGAS 08.10.2020 18:38

1a)3/20 б)2,4

ПОКАЗАТЬ ОТВЕТЫ

Denkuzo176 08.10.2020 18:38

$1a) 1\frac{1}{3}x = 0,3\\ \\x = \frac{3}{10} : \frac{4}{3} = \frac{3*3}{10*4} = \frac{9}{40}$

$1b) 1\frac{1}{4}x = 5,5\\ \\1,25x = 5,5\\\\x = 5,5 : 1,25 = 4,4$

$2a) a + 0,2a + \frac{3}{7}a = 1\\ \\\frac{6}{5}a + \frac{3}{7}a = 1 \\\\\frac{42+15}{35}a = 1\\\\\frac{57}{35} a = 1\\ \\a = \frac{35}{57}$

$2b) b + \frac{1}{4}b + 0,75b = 1\\ \\b + 0,25b + 0,75b = 1\\\\2b = 1\\\\b = 0,5$

$3a) 3,8(b-1\frac{1}{6}) = \frac{19}{20}\\ \\\frac{19}{5}b - (\frac{19}{5} : \frac{7}{6}) = \frac{19}{20}\\\\\frac{19}{5}b - \frac{19*6}{5*7} = \frac{19}{20}\\\\\frac{19}{5}b = \frac{19}{20} + \frac{114}{35}\\\\\frac{19}{5}b = \frac{133+456}{140} = \frac{589}{140}\\\\b = \frac{589*5}{140*19} = \frac{31}{28} = 1\frac{3}{28}$

$3b) 1\frac{1}{4}(b -1,2) = 5,5\\\\1,25b - 1,5 = 5,5\\\\1,25b = 5,5 + 1,5\\\\1,25b = 7\\\\b = 7 : 1,25\\\\b = 5,6$

$4a) (m-\frac{3}{7}) : 1\frac{1}{5} = 3,5\\ \\m - \frac{3}{7} = \frac{7}{2} * \frac{6}{5}\\ \\m - \frac{3}{7} = \frac{21}{5}\\ \\m = \frac{21}{5} + \frac{3}{7} = \frac{147+15}{35} \\ \\m = \frac{162}{35} = 4\frac{22}{35}$

$4b) (2,3 - m) : \frac{3}{5} = 0,12\\ \\2,3 - m = 0,12 * 0,6\\\\2,3 - m = 0,72\\\\m = 2,3 - 0,72\\\\m = 1,58$

$5a) \frac{17}{4,3-c} = 5,1\\\\4,3 - c = \frac{17}{5,1} = 17 : \frac{51}{10} = \frac{17*10}{51} = \frac{10}{3}\\ \\c = \frac{43}{10} - \frac{10}{3} = \frac{129-100}{30} = \frac{29}{30}$

$5b) \frac{0,4}{c - \frac{3}{4}} = 1\frac{1}{3}\\ \\c - \frac{3}{4} = \frac{2}{5} : \frac{4}{3}\\ \\c - \frac{3}{4} = \frac{2*3}{5*4} = \frac{6}{20} = \frac{3}{10}\\\\c = 0,3 + 0,75\\\\c = 1,05$

$6a) 5x - \frac{1}{2} = \frac{5}{6}\\ \\5x = \frac{5}{6} + \frac{1}{2} \\\\5x = \frac{5+3}{6} = \frac{8}{6} = \frac{4}{3}\\ \\x = \frac{4}{3} : 5 = \frac{4}{3} * \frac{1}{5} = \frac{4}{15}$

$6b) 2\frac{5}{6} - 5x = 1\frac{1}{3}\\ \\5x = 2\frac{5}{6} - 1\frac{1}{3} \\ \\5x = \frac{17}{6} - \frac{4}{3} = \frac{17-8}{6} = \frac{9}{6}\\ \\5x = 1,5\\\\x = 1,5 : 5\\\\x = 0,3$

$7a) (2t - 3\frac{4}{15}) * 1,3 = \frac{13}{25}\\ \\2,6t - \frac{49}{15}* \frac{13}{10} = \frac{13}{25}\\ \\2,6t = \frac{13}{25} + \frac{637}{150}\\ \\2,6t = \frac{78+637}{150} = \frac{715}{150}\\ \\t = \frac{715}{150} : \frac{13}{5} = \frac{715*5}{150*13} = \frac{55}{30} = 1\frac{25}{30} = 1\frac{5}{6}$

$7b) 2,25 + 0,5(11-3x) = 4\frac{3}{8}]\\ \\2,25 + 5,5 - 1,5x = 4,375\\\\7,75 - 1,5x = 4,375\\\\1,5x = 7,75 - 4,375\\\\1,5x = 3,375\\\\x = 3,375 : 1,5\\\\x = 2,25$

$8a) 6 - (2,2x - 1\frac{1}{7}) * 1\frac{1}{6} = 5,5\\ \\6 - (\frac{11}{5}x * \frac{7}{6} + \frac{8}{7}*\frac{7}{6}) = 5,5\\ \\\frac{11}{5}x * \frac{7}{6} + \frac{8}{7}*\frac{7}{6} = 6 - 5,5\\\\\frac{11}{5}x * \frac{7}{6} + \frac{8}{7}*\frac{7}{6} = 0,5\\\\\frac{77}{30}x + \frac{4}{3} = \frac{1}{2}\\\\\frac{77}{30}x = \frac{1}{2} - \frac{4}{3} =\frac{3-8}{6}\\\\\frac{77}{30}x = -\frac{5}{6}\\ \\x = -\frac{5}{6} : \frac{77}{30} = -\frac{5*30}{6*77} = -\frac{25}{77}$

$8b) 5\frac{6}{7}(2\frac{1}{4} - 0,25x) = 0,41\\ \\2,25 - 0,25x = \frac{41}{100} : \frac{41}{7} = \frac{41*7}{100*41} = 0,07\\ \\0,25x = 2,25 - 0,07 = 2,18\\\\x = 2,18 : 0,25 \\\\x = 8,72$