Đáp án:
a, $\dfrac{-5}{28}$
b, $\dfrac{2}{5}$
c, $\dfrac{-77}{120}$
d, $\dfrac{-23}{24}$
e, $\dfrac{-2}{5}$
g, $\dfrac{-176}{405}$
Giải thích các bước giải:
a,
$\dfrac{11}{13}-\left ( \dfrac{5}{42}-x \right )= -\left ( \dfrac{15}{28}-\dfrac{11}{13} \right )$
$= \dfrac{-15}{28}+\dfrac{11}{13}$
$\Rightarrow \dfrac{5}{42}-x= \dfrac{15}{28}\Rightarrow x= \dfrac{5}{42}-\dfrac{15}{28}= \dfrac{-5}{28}$
b,
$x+\dfrac{1}{3}= \dfrac{2}{5}-\left ( \dfrac{-1}{3} \right )= \dfrac{2}{5}+\dfrac{1}{3}$
$\Rightarrow x= \dfrac{2}{5}$
c,
$\dfrac{-5}{8}-x= \dfrac{-3}{20}-\dfrac{-1}{6}= \dfrac{-3}{20}+\dfrac{1}{6}= \dfrac{1}{62}$
$\Rightarrow x= \dfrac{-77}{120}$
d,
$x-\left ( -\dfrac{1}{4} \right )= \dfrac{-5}{6}+\dfrac{1}{8}$
$\Rightarrow x= \dfrac{-5}{6}+\dfrac{1}{8}-\dfrac{1}{4}= \dfrac{-23}{24}$
e,
$\dfrac{-2x}{3}= \dfrac{4}{15}$
$\Rightarrow x= \dfrac{4}{15}:\dfrac{-2}{3}= \dfrac{-2}{5}$
g,
$x:\dfrac{22}{15}= \dfrac{-8}{27}$
$\Rightarrow x= \dfrac{-8}{27}.\dfrac{22}{15}= \dfrac{-176}{405}$
