Question

Решить уравнения письменно, хелп

Answer 1

5)
а)
$\frac{17}{4.3 - c} = 5.1 \\ 4.3 - c = 17 \div 5.1 \\ 4.3 - c = 17 \times \frac{10}{51} \\ 4.3 - c = \frac{10}{3} \\ c = 4.3 - \frac{10}{3} = \frac{43}{10} - \frac{10}{3} = \frac{129}{30} - \frac{100}{30} = \frac{29}{30}$
б)
$\frac{0.4}{c - \frac{3}{4} } = 1 \frac{1}{3} \\ c - \frac{3}{4} = 0.4 \div 1 \frac{1}{3} \\ c - \frac{3}{4} = \frac{4}{10} \div \frac{4}{3} \\ c - \frac{3}{4} = \frac{4}{10} \times \frac{3}{4} \\ c - \frac{3}{4} = \frac{3}{10} \\ c = \frac{3}{10} + \frac{3}{4} = \frac{6}{20} + \frac{15}{20} = \frac{21}{20} = 1 \frac{1}{20}$

6)
а)
$5x - \frac{1}{2} = \frac{5}{6} \\ 5x = \frac{5}{6} + \frac{1}{2} \\ 5x = \frac{5}{6} + \frac{3}{6} \\ 5x = \frac{8}{6} \\ x = \frac{8}{6} \div 5 = \frac{8}{6} \times \frac{1}{5} = \frac{4}{3} \times \frac{1}{5} = \frac{4}{15}$
б)
$2 \frac{5}{6} - 5x = 1 \frac{1}{3} \\ 5x = 2 \frac{5}{6} - 1 \frac{1}{3} \\ 5x = \frac{17}{6} - \frac{4}{3} \\ 5x = \frac{17}{6} - \frac{8}{6} \\ 5x = \frac{9}{6} \\ 5x = \frac{3}{2} \\ x = \frac{3}{2} \div 5 = \frac{3}{2} \times \frac{1}{5} = \frac{3}{10}$