Đáp án:
$1)
x=\dfrac{7}{6}\\
2) x=\dfrac{-7}{10}\\
3)
x=\dfrac{-9}{12}\\
4)
x=\dfrac{15}{2}\\
5)
x=\dfrac{-28}{15}\\
6)
x=\dfrac{209}{45}\\
7)
x=\dfrac{13}{20}\\$
Giải thích các bước giải:
$1)
\dfrac{1}{2}+x=\dfrac{5}{3}\\
\Leftrightarrow x=\dfrac{5}{3}-\dfrac{1}{2}\\
\Leftrightarrow x=\dfrac{10}{6}-\dfrac{3}{6}\\
\Leftrightarrow x=\dfrac{7}{6}\\
2) \dfrac{4}{5}-x=\dfrac{3}{2}\\
\Leftrightarrow x=\dfrac{4}{5}-\dfrac{3}{2}\\
\Leftrightarrow x=\dfrac{8}{10}-\dfrac{15}{10}\\
\Leftrightarrow x=\dfrac{-7}{10}\\
3)
x+\dfrac{5}{6}=\dfrac{1}{12}\\
\Leftrightarrow x=\dfrac{1}{12}-\dfrac{5}{6}\\
\Leftrightarrow x=\dfrac{1}{12}-\dfrac{10}{12}\\
\Leftrightarrow x=\dfrac{-9}{12}\\
4)
10-x=\dfrac{5}{2}\\
\Leftrightarrow x=10-\dfrac{5}{2}\\
\Leftrightarrow x=\dfrac{20}{2}-\dfrac{5}{2}\\
\Leftrightarrow x=\dfrac{15}{2}\\
5)
x+2=\dfrac{1}{3}-\dfrac{1}{5}\\
\Leftrightarrow x=\dfrac{1}{3}-\dfrac{1}{5}-2\\
\Leftrightarrow x=\dfrac{5}{15}-\dfrac{3}{15}-\dfrac{30}{15}\\
\Leftrightarrow x=\dfrac{-28}{15}\\
6)
x-4=\dfrac{1}{5}-\left ( \dfrac{1}{9}-\dfrac{5}{9} \right )\\
\Leftrightarrow x=\dfrac{1}{5}-\dfrac{-4}{9}+4\\
\Leftrightarrow x=\dfrac{9}{45}+\dfrac{20}{45}+\dfrac{180}{45}\\
\Leftrightarrow x=\dfrac{209}{45}\\
7)
x-\dfrac{1}{5}=\dfrac{1}{5}-\left ( \dfrac{1}{4}-\dfrac{2}{4} \right )\\
\Leftrightarrow x=\dfrac{1}{5}-\dfrac{-1}{4}+\dfrac{1}{5}\\
\Leftrightarrow x=\dfrac{2}{5}+\dfrac{1}{4}\\
\Leftrightarrow x=\dfrac{8}{20}+\dfrac{5}{20}\\
\Leftrightarrow x=\dfrac{13}{20}\\$
