а) 2(3x + 4) = 20 - 6(2 - x);

### № 2 а) $\frac{1}{2}(x + \frac{4}{5}) - (\frac{1}{5} - x) = \frac{1}{2}x + \frac{2}{5} - \frac{1}{5} + x = \frac{3}{2}x + \frac{1}{5}$ б) $-\frac{2}{3}(\frac{6}{7} - y) + (\frac{2}{7} + y) = -\frac{12}{21} + \frac{2}{3}y + \frac{2}{7} + y = -\frac{4}{7} + \frac{2}{7} + \frac{5}{3}y = -\frac{2}{7} + \frac{5}{3}y$ в) $-(y + \frac{1}{8}) + \frac{3}{4}(2 + y) = -y - \frac{1}{8} + \frac{6}{4} + \frac{3}{4}y = -\frac{1}{4}y + \frac{11}{8}$ г) $\frac{1}{9}(\frac{3}{5} - x) - (x - \frac{1}{15}) = \frac{3}{45} - \frac{1}{9}x - x + \frac{1}{15} = \frac{1}{15} - \frac{10}{9}x + \frac{1}{15} = \frac{2}{15} - \frac{10}{9}x$ ### № 3 а) $\frac{3}{15}(x + 5) - (\frac{1}{5} - x) = \frac{1}{5}x + 1 - \frac{1}{5} + x = \frac{6}{5}x + \frac{4}{5}$ б) $-\frac{9}{14}(2 - y) + (\frac{2}{7} - y) = -\frac{18}{14} + \frac{9}{14}y + \frac{4}{14} - y = -\frac{14}{14} - \frac{5}{14}y = -1 - \frac{5}{14}y$ в) $-\frac{5}{17}(5 + x) - \frac{2}{3}(x - \frac{15}{34}) = -\frac{25}{17} - \frac{5}{17}x - \frac{2}{3}x + \frac{30}{102} = -\frac{150}{102} - \frac{15}{51}x - \frac{34}{51}x + \frac{30}{102} = -\frac{120}{102} - \frac{49}{51}x = -\frac{20}{17} - \frac{49}{51}x$ г) $\frac{7}{12}(4 - y) - (y + \frac{11}{12}) = \frac{28}{12} - \frac{7}{12}y - y - \frac{11}{12} = \frac{17}{12} - \frac{19}{12}y$ ### Блок 4. Уравнения. № 1 а) $24x + 8 = 15x - 100 \Rightarrow 9x = -108 \Rightarrow x = -12$ б) $76 - 45x = 94x - 341 \Rightarrow -139x = -417 \Rightarrow x = 3$ в) $-52x + 101 = 119 - 96x \Rightarrow 44x = 18 \Rightarrow x = \frac{18}{44} = \frac{9}{22}$ г) $78 + 39x = 306 - 18x \Rightarrow 57x = 228 \Rightarrow x = 4$ ### Найди множество корней уравнения: а) $2(3x + 4) = 20 - 6(2 - x) \Rightarrow 6x + 8 = 20 - 12 + 6x \Rightarrow 6x + 8 = 8 + 6x \Rightarrow 0 = 0$. Уравнение верно при любом значении x. б) $1,6x + 0,8 = -0,3(4 - 5x) \Rightarrow 1,6x + 0,8 = -1,2 + 1,5x \Rightarrow 0,1x = -2 \Rightarrow x = -20$ в) $7x - 4(2x + 3) = 4(x - 2) - 5(x + 4) \Rightarrow 7x - 8x - 12 = 4x - 8 - 5x - 20 \Rightarrow -x - 12 = -x - 28$. Нет корней. г) $2,4 + 4(-0,1x + 0,8) = 1,7x - 5(0,3x - 1) \Rightarrow 2,4 - 0,4x + 3,2 = 1,7x - 1,5x + 5 \Rightarrow 5,6 - 0,4x = 0,2x + 5 \Rightarrow 0,6 = 0,6x \Rightarrow x = 1$