a) \(\dfrac{1}{7}=\dfrac{8}{-x}\)
\(\Leftrightarrow1.\left(-x\right)=7.8\)
\(\Leftrightarrow-x=56\)
\(\Leftrightarrow x=-56\)
c) \(4\dfrac{2}{5}:\left(-\dfrac{33}{10}\right)+x=-1\dfrac{5}{6}\)
\(\Leftrightarrow\dfrac{22}{5}:\left(-\dfrac{33}{10}\right)+x=-\dfrac{11}{6}\)
\(\Leftrightarrow\dfrac{22}{10}.\left(-\dfrac{10}{33}\right)+x=-\dfrac{11}{6}\)
\(\Leftrightarrow-\dfrac{2}{3}+x=-\dfrac{11}{6}\)
\(\Leftrightarrow x=\left(-\dfrac{11}{6}\right)-\left(-\dfrac{2}{3}\right)\)
\(\Leftrightarrow x=-\dfrac{7}{6}\)
d) \(45\%.x-2\dfrac{3}{8}=-1\dfrac{31}{40}\)
\(\Leftrightarrow45\%.x=\left(-1\dfrac{31}{40}\right)+2\dfrac{3}{8}\)
\(\Leftrightarrow45\%.x=1\dfrac{23}{20}\)
\(\Leftrightarrow\dfrac{9}{20}x=\dfrac{43}{20}\)
\(\Leftrightarrow x=\dfrac{43}{20}:\dfrac{9}{20}\)
\(\Leftrightarrow x=\dfrac{43}{9}\)
a, \(\dfrac{1}{7}=\dfrac{8}{-x}\Rightarrow-x=8.7\Leftrightarrow x=-56\)
b , \(\dfrac{3x}{9}=\dfrac{2}{6}\Leftrightarrow\dfrac{x}{3}=\dfrac{1}{3}\Leftrightarrow x=1\)
c, \(4\dfrac{2}{5}:\left(\dfrac{-33}{10}\right)+x=-1\dfrac{5}{6}\)
<=> \(\dfrac{22}{5}.\dfrac{10}{-33}+x=-1\dfrac{5}{6}\)
<=> \(\dfrac{-4}{3}\)+ x =\(\dfrac{-11}{6}\) \(\Leftrightarrow x=\dfrac{-1}{2}\)
d , \(45\%x-2\dfrac{3}{8}=-1\dfrac{31}{40}\)
<=> 0,45x - \(\dfrac{19}{8}\) = \(\dfrac{-71}{40}\)
<=> 0,45x = \(\dfrac{3}{5}\)=> x=\(\dfrac{4}{3}\)
b) \(\dfrac{3x}{9}=\dfrac{2}{6}\)
\(\Leftrightarrow3x.6=9.2\)
\(\Leftrightarrow18x=18\)
\(\Leftrightarrow x=18:18\)
\(\Leftrightarrow x=1\)
1,\(\dfrac{1}{7}=\dfrac{8}{-x}\Leftrightarrow-x=56\Leftrightarrow x=-56\)
2,\(\dfrac{3x}{9}=\dfrac{2}{6}\Leftrightarrow\dfrac{x}{3}=\dfrac{1}{3}\Leftrightarrow x=1\)
3,\(4\dfrac{2}{5}:\left(\dfrac{-33}{10}\right)+x=-1\dfrac{5}{6}\Leftrightarrow\dfrac{22}{5}:\left(\dfrac{-33}{10}\right)+x=\dfrac{-11}{6}\Leftrightarrow\dfrac{-4}{3}+x=\dfrac{-11}{6}\Leftrightarrow x=\dfrac{-1}{2}\\ \\ \\ \\ \\ \\ \\ 4,45\%.x-2\dfrac{3}{8}=-1\dfrac{31}{40}\Leftrightarrow45\%.x-\dfrac{19}{8}=\dfrac{-71}{40}\Leftrightarrow45\%.x=\dfrac{3}{5}\Leftrightarrow x=\dfrac{1}{75}\)
