Đáp án:
$a)
x=\dfrac{5}{2}\\
b)
x=\dfrac{-13}{11}\\
c)
x=\dfrac{-27}{28}\\
d)
x=2\\$
Giải thích các bước giải:
$a)
\dfrac{1}{12}x-\dfrac{75}{100}x=-1\dfrac{2}{3}\\
\Leftrightarrow \dfrac{1}{12}x-\dfrac{3}{4}x=\dfrac{-5}{3}\\
\Leftrightarrow \dfrac{1}{12}x-\dfrac{9}{12}x=\dfrac{-5}{3}\\
\Leftrightarrow \dfrac{-8}{12}x=\dfrac{-5}{3}\\
\Leftrightarrow \dfrac{-2}{3}x=\dfrac{-5}{3}\\
\Leftrightarrow x=\dfrac{-5}{3}.\dfrac{-3}{2}=\dfrac{5}{2}\\
b)
4,5-2x.\left ( -1\dfrac{4}{7} \right )=\dfrac{11}{14}\\
\Leftrightarrow \dfrac{9}{2}-2x.\dfrac{-11}{7}=\dfrac{11}{14}\\
\Leftrightarrow \dfrac{22}{7}x=\dfrac{11}{14}-\dfrac{9}{2}\\
\Leftrightarrow \dfrac{22}{7}x=\dfrac{11}{14}-\dfrac{9.7}{14}\\
\Leftrightarrow \dfrac{22}{7}x=\dfrac{-52}{14}=\dfrac{-26}{7}\\
\Leftrightarrow x=\dfrac{-26}{7}.\dfrac{7}{22}=\dfrac{-13}{11}\\
c)
-\dfrac{2}{3}x-\dfrac{4}{7}=\dfrac{1}{14}\\
\Leftrightarrow -\dfrac{2}{3}x=\dfrac{4}{7}+\dfrac{1}{14}\\
\Leftrightarrow \dfrac{-2}{3}x=\dfrac{8}{14}+\dfrac{1}{14}\\
\Leftrightarrow \dfrac{-2}{3}x=\dfrac{9}{14}\\
\Leftrightarrow x=\dfrac{9}{14}.\dfrac{-3}{2}=\dfrac{-27}{28}\\
d)
\left ( \dfrac{-2x}{5}+1 \right ):(-5)=\dfrac{-1}{25}\\
\Leftrightarrow \dfrac{-2x}{5}+1 =\dfrac{-1}{25}.(-5)=\dfrac{1}{5}\\
\Leftrightarrow \dfrac{-2x}{5}=\dfrac{1}{5}-1\\
\Leftrightarrow \dfrac{-2x}{5}=\dfrac{1}{5}-\dfrac{5}{5}=\dfrac{-4}{5}\\
\Leftrightarrow x=\dfrac{-4}{5}.\dfrac{-5}{2}=2\\$
