Đáp án:
B2:
b) \(x = - \dfrac{9}{2}\)
Giải thích các bước giải:
\(\begin{array}{l}
B1:\\
1) - \dfrac{5}{7}.\dfrac{2}{{11}} - \dfrac{5}{7}.\dfrac{9}{{11}} + 1 + \dfrac{5}{7}\\
= - \dfrac{5}{7}.\left( {\dfrac{2}{{11}} + \dfrac{9}{{11}} - 1} \right) + 1\\
= - \dfrac{5}{7}.\left( {1 - 1} \right) + 1 = 1\\
2)\dfrac{6}{7} + \dfrac{5}{{5.8}} - \dfrac{3}{{16}}.4\\
= \dfrac{6}{7} + \dfrac{1}{8} - \dfrac{3}{4} = \dfrac{{13}}{{56}}\\
c)\dfrac{2}{3} + \dfrac{1}{3}.\dfrac{7}{{18}}.\dfrac{{12}}{7}\\
= \dfrac{2}{3} + \dfrac{1}{3}.\dfrac{2}{3}\\
= \dfrac{2}{3} + \dfrac{2}{9} = \dfrac{8}{9}\\
B2:\\
a)\dfrac{3}{4}x + \dfrac{5}{2} = - \dfrac{3}{{16}}\\
\to \dfrac{3}{4}x = - \dfrac{{43}}{{16}}\\
\to x = - \dfrac{{43}}{{12}}\\
b)\dfrac{1}{3}x - \dfrac{1}{2}x = \dfrac{3}{4}\\
\to - \dfrac{1}{6}x = \dfrac{3}{4}\\
\to x = - \dfrac{9}{2}
\end{array}\)
