Đáp án:
b) \(x = - \dfrac{{22}}{7}\)
Giải thích các bước giải:
\(\begin{array}{l}
a)\dfrac{1}{5}x + \dfrac{2}{3} = \dfrac{5}{6}\\
\to \dfrac{1}{5}x = \dfrac{5}{6} - \dfrac{2}{3}\\
\to \dfrac{1}{5}x = \dfrac{1}{6}\\
\to x = \dfrac{5}{6}\\
c)\dfrac{2}{9} + \dfrac{5}{6}x = \dfrac{2}{3}.\dfrac{7}{4}\\
\to \dfrac{2}{9} + \dfrac{5}{6}x = \dfrac{7}{6}\\
\to \dfrac{5}{6}x = \dfrac{7}{6} - \dfrac{2}{9}\\
\to \dfrac{5}{6}x = \dfrac{{17}}{{18}}\\
\to x = \dfrac{{17}}{{15}}\\
b)\dfrac{7}{2} + \dfrac{7}{8}x = \dfrac{3}{4}\\
\to \dfrac{7}{8}x = \dfrac{3}{4} - \dfrac{7}{2}\\
\to \dfrac{7}{8}x = \dfrac{{ - 11}}{4}\\
\to x = - \dfrac{{22}}{7}\\
d)x:\dfrac{9}{{11}} + \dfrac{{12}}{{121}} = \dfrac{1}{6}.\dfrac{5}{{12}}\\
\to \dfrac{{9x}}{{11}} + \dfrac{{12}}{{121}} = \dfrac{5}{{72}}\\
\to \dfrac{{99x + 12}}{{121}} = \dfrac{5}{{72}}\\
\to 99x + 12 = \dfrac{{605}}{{72}}\\
\to 99x = - \dfrac{{259}}{{72}}\\
\to x = - \dfrac{{259}}{{7128}}
\end{array}\)
