Đáp án:
B2:
c) \(\left[ \begin{array}{l}
x = 1\\
x = \dfrac{1}{2}
\end{array} \right.\)
Giải thích các bước giải:
\(\begin{array}{l}
B1:\\
c)\left( { - \sqrt {\dfrac{9}{4}} + 4\sqrt {{{\left( { - \dfrac{{43}}{{20}}} \right)}^2}} - 9.\dfrac{7}{6}} \right).\sqrt {\dfrac{{25}}{{16}}} \\
= \left( { - \dfrac{3}{4} + 4.\dfrac{{43}}{{20}} - \dfrac{{21}}{2}} \right).\dfrac{5}{4}\\
= - \dfrac{{53}}{{20}}.\dfrac{5}{4} = - \dfrac{{53}}{{16}}\\
d)\dfrac{{ - 1}}{{15}} + \dfrac{4}{9}:\dfrac{8}{9} - \dfrac{5}{6}\\
= \dfrac{{ - 1}}{{15}} + \dfrac{1}{2} - \dfrac{5}{6} = - \dfrac{2}{5}\\
B2:\\
a)x:\left( { - \dfrac{{31}}{{15}}} \right) + \dfrac{7}{2} = - \dfrac{3}{4}\\
\to x:\left( { - \dfrac{{31}}{{15}}} \right) = - \dfrac{{17}}{4}\\
\to x = \dfrac{{527}}{{60}}\\
b) - \dfrac{5}{8} - x:\dfrac{{23}}{6} + \dfrac{{31}}{4} = - 2\\
\to x:\dfrac{{23}}{6} = - \dfrac{5}{8} + \dfrac{{31}}{4} + 2\\
\to x:\dfrac{{23}}{6} = \dfrac{{73}}{8}\\
\to x = \dfrac{{1679}}{{48}}\\
c)\left| {x - \dfrac{3}{4}} \right| = \dfrac{1}{4}\\
\to \left[ \begin{array}{l}
x - \dfrac{3}{4} = \dfrac{1}{4}\\
x - \dfrac{3}{4} = - \dfrac{1}{4}
\end{array} \right.\\
\to \left[ \begin{array}{l}
x = 1\\
x = \dfrac{1}{2}
\end{array} \right.
\end{array}\)
