Đáp án:

 Em xem hình.

Giải thích các bước giải:

Đáp án:

 $a)x=\dfrac{3}{2}\\
b)
 x=\dfrac{7}{12}\\
c)
 x=\dfrac{-1}{2}\\
d)
x=-1\\
e)
x=\dfrac{-27}{28}\\
f)
 x=\dfrac{-45}{44}\\
g)
x=\dfrac{10}{13}\\
i)
x=\dfrac{-9}{20}$

Giải thích các bước giải:

 $a)\dfrac{3}{4}:x=\dfrac{1}{2}\\
\Leftrightarrow \dfrac{3}{4}.\dfrac{1}{x}=\dfrac{1}{2}\\
\Leftrightarrow x=\dfrac{3}{4}.2=\dfrac{3}{2}\\
b)
\dfrac{3}{4}-x=\dfrac{1}{6}\\
\Leftrightarrow x=\dfrac{3}{4}-\dfrac{1}{6}\\
\Leftrightarrow x=\dfrac{9}{12}-\dfrac{2}{12}\\
\Leftrightarrow x=\dfrac{7}{12}\\
c)
\dfrac{-4}{9}.x-\dfrac{7}{18}=\dfrac{-1}{6}\\
\Leftrightarrow \dfrac{-4}{9}.x=\dfrac{-1}{6}+\dfrac{7}{18}\\
\Leftrightarrow \dfrac{-4}{9}.x=\dfrac{-3}{18}+\dfrac{7}{18}\\
\Leftrightarrow \dfrac{-4}{9}x=\dfrac{4}{18}=\dfrac{2}{9}\\
\Leftrightarrow x=\dfrac{2}{9}.\dfrac{-9}{4}=\dfrac{-1}{2}\\
d)
\left ( x+1\dfrac{2}{3} \right ).\dfrac{4}{7}=\dfrac{8}{21}\\
\Leftrightarrow  x+\dfrac{5}{3} =\dfrac{8}{21}.\dfrac{7}{4}\\
\Leftrightarrow  x+\dfrac{5}{3} =\dfrac{2}{3}\\
\Leftrightarrow x=\dfrac{2}{3}-\dfrac{5}{3}=\dfrac{-3}{3}=-1\\
e)
\dfrac{-5}{7}-x=\dfrac{7}{12}+\dfrac{-1}{3}\\
\Leftrightarrow x=\dfrac{-5}{7}-\dfrac{7}{12}+\dfrac{1}{3}\\
\Leftrightarrow x=\dfrac{-5.12}{84}-\dfrac{7.7}{84}+\dfrac{28}{84}\\
\Leftrightarrow x=\dfrac{-60-49+28}{84}=\dfrac{-81}{84}=\dfrac{-27}{28}\\
f)
\left ( 3\dfrac{1}{2}+2x \right ).3\dfrac{2}{3}=5\dfrac{1}{3}\\
\Leftrightarrow \left ( \dfrac{7}{2}+2x \right ).\dfrac{11}{3}=\dfrac{16}{3}\\
\Leftrightarrow \dfrac{7}{2}+2x=\dfrac{16}{3}.\dfrac{3}{11}=\dfrac{16}{11}\\
\Leftrightarrow 2x=\dfrac{16}{11}-\dfrac{7}{2}\\
\Leftrightarrow 2x=\dfrac{16.2}{22}-\dfrac{7.11}{22}\\
\Leftrightarrow 2x=\dfrac{-45}{22}\\
\Leftrightarrow x=\dfrac{-45}{44}\\
g)
x+\dfrac{40}{100}x=-1,4\\
\Leftrightarrow \dfrac{10}{10}x+\dfrac{4}{10}x=\dfrac{-14}{10}\\
\Leftrightarrow \dfrac{14}{10}x=\dfrac{-14}{10}\\
\Leftrightarrow x=\dfrac{-14}{10}.\dfrac{10}{14}=-1\\
h)\dfrac{2}{3}x-\dfrac{1}{8}x=\dfrac{5}{12}\\
\Leftrightarrow \left ( \dfrac{2}{3}-\dfrac{1}{8} \right )x=\dfrac{5}{12}\\
\Leftrightarrow \left (\dfrac{16}{24}-\dfrac{3}{24}  \right )x=\dfrac{5}{12}\\
\Leftrightarrow \dfrac{13}{24}x=\dfrac{5}{12}\\
\Leftrightarrow x=\dfrac{5}{12}.\dfrac{24}{13}=\dfrac{10}{13}\\
i)
x=(-3,2).\dfrac{-15}{64}+\left ( 0,8-2\dfrac{4}{15} \right ):3\dfrac{2}{3}\\
=\dfrac{32}{10}.\dfrac{15}{64}+\left ( \dfrac{8}{10}-\dfrac{34}{15} \right ):\dfrac{11}{3}\\
=\dfrac{16}{5}.\dfrac{15}{64}+\left ( \dfrac{4}{5}-\dfrac{34}{15} \right ):\dfrac{11}{3}\\
=\dfrac{3}{4}+\left ( \dfrac{12}{15}-\dfrac{34}{15} \right ).\dfrac{3}{11}\\
=\dfrac{3}{4}-\dfrac{22}{15}.\dfrac{3}{11}\\
=\dfrac{3}{4}-\dfrac{6}{5}\\
=\dfrac{15}{20}-\dfrac{24}{20}\\
=\dfrac{-9}{20}$