Question

2вычислите (1. 1/3 - 2. 5/6): (0.75-1. 1/6) (-1.25+1. 7/8): (-1. 1/12-0/5) 3 решить уровнения а)2*(0.4х-1.2)=х+1.4 б)х-1. 2/7=4x+2. 5/14 в)3*(0.4x+1.4)=x-0.8 г) 3x+1. 2/9+x-3. 10/27 4 решить пример 4/7*(1.4*-1. 7/8 - 3.5)+1.2*(3-2*-1. 7/8)

Answer 1

$(1 \frac{1}{3} - 2 \frac{5}{6}):(0.75-1 \frac{1}{6})=( \frac{4}{3} - \frac{17}{6}):( \frac{3}{4}- \frac{7}{6})= \\\ =( \frac{8}{6} - \frac{17}{6}):( \frac{9}{12}- \frac{14}{12})=- \frac{9}{6} :(- \frac{5}{12})=\frac{9}{6}\cdot \frac{12}{5}= \frac{108}{30} =3.6 \\\ (-1.25+1 \frac{7}{8}):(-1 \frac{1}{12}- \frac{0}{5})=(- \frac{5}{4}+\frac{15}{8}):(- \frac{13}{12})=(- \frac{10}{8}+\frac{15}{8}):(- \frac{13}{12})= \\\ = \frac{5}{8}\cdot(- \frac{12}{13})=- \frac{60}{104}=- \frac{15}{26}$
$2(0.4x-1.2)=x+1.4 \\\ 0.8x-2.4=x+1.4 -0.2x=3.8 \\\ x=-19$
$x-1 \frac{2}{7}=4x+2 \frac{5}{14} \\\ x- \frac{9}{7}=4x+ \frac{33}{14} \\\ 14x-18=56x+33 \\\ -42x=51 \\\ x=- \frac{51}{42} =- \frac{17}{14}$
$3(0.4x+1.4)=x-0.8 \\\ 1.2x+4.2=x-0.8 \\\ 0.2x=-5 \\\ x=-25$
$3x+1 \frac{2}{9}+x-3 \frac{10}{27}=0 \\\ 3x+ \frac{11}{9}+x-\frac{91}{27}=0 \\\ 81x+ 33+27x-91=0 \\\ 108x=58 \\\ x= \frac{58}{108} =\frac{29}{54}$
$\frac{4}{7}(1.4\cdot(-1 \frac{7}{8})- 3.5)+1.2(3-2\cdot(-1 \frac{7}{8}))= \\\ = \frac{4}{7}(-2.625- 3.5)+1.2(3+3.75)= \frac{4}{7}\cdot(-6.125)+1.2\cdot6.75= \\\ =-3.5+8.1=4.6$