Đáp án:
\(\begin{array}{l}
a)x = \dfrac{1}{6}\\
b)x = - \dfrac{{77}}{{120}}\\
c)x = - \dfrac{2}{5}\\
d)x = - \dfrac{{23}}{{24}}\\
e)x = - \dfrac{5}{8}\\
f)x = 13\\
g)x = \dfrac{{13}}{8}\\
h)x = - \dfrac{{87}}{{140}}\\
i)x = \dfrac{{27}}{2}\\
k)x = \dfrac{3}{{10}}\\
l)x = - \dfrac{1}{{11}}
\end{array}\)
Giải thích các bước giải:
\(\begin{array}{l}
a) - \dfrac{2}{{15}} - \left( { - \dfrac{3}{{10}}} \right) = x\\
\to x = \dfrac{1}{6}\\
b) - \dfrac{5}{8} - \left( { - \dfrac{3}{{20}}} \right) - \dfrac{1}{6} = x\\
\to x = - \dfrac{{77}}{{120}}\\
c)x = \dfrac{4}{{15}}:\left( { - \dfrac{2}{3}} \right)\\
\to x = - \dfrac{2}{5}\\
d)x = - \dfrac{5}{6} + \dfrac{1}{8} - \dfrac{1}{4}\\
\to x = - \dfrac{{23}}{{24}}\\
e)\dfrac{{2x}}{5} - 1 = \dfrac{1}{4}.\left( { - 5} \right)\\
\to \dfrac{{2x}}{5} = - \dfrac{5}{4} + 1\\
\to \dfrac{{2x}}{5} = - \dfrac{1}{4}\\
\to x = - \dfrac{5}{8}\\
f)\dfrac{9}{4}x - \dfrac{{37}}{4} = 20\\
\to \dfrac{9}{4}x = \dfrac{{117}}{4}\\
\to x = 13\\
g)\left( {\dfrac{{13}}{4}:x} \right).\left( { - \dfrac{5}{4}} \right) = - \dfrac{5}{2}\\
\to \dfrac{{13}}{4}:x = 2\\
\to x = \dfrac{{13}}{8}\\
h)\dfrac{2}{3}x = \dfrac{3}{{10}} - \dfrac{5}{7}\\
\to \dfrac{2}{3}x = - \dfrac{{29}}{{70}}\\
\to x = - \dfrac{{87}}{{140}}\\
i)\dfrac{3}{4}:x = - \dfrac{1}{4} + \dfrac{{11}}{{36}}\\
\to \dfrac{3}{4}:x = \dfrac{1}{{18}}\\
\to x = \dfrac{{27}}{2}\\
k) - \dfrac{6}{5} + x = \left( { - \dfrac{7}{4} + 2} \right).\left( { - \dfrac{{18}}{5}} \right)\\
\to - \dfrac{6}{5} + x = - \dfrac{9}{{10}}\\
\to x = \dfrac{3}{{10}}\\
l) - \dfrac{{22}}{{15}}x + \dfrac{1}{3} = \dfrac{7}{{15}}\\
\to - \dfrac{{22}}{{15}}x = \dfrac{2}{{15}}\\
\to x = - \dfrac{1}{{11}}
\end{array}\)
