Đáp án:
$\begin{array}{l}
7)a)A = \left( { - \frac{3}{4} + \frac{2}{3}} \right):\frac{5}{{11}} + \left( { - \frac{1}{4} + \frac{1}{3}} \right):\frac{5}{{11}}\\
= \left( { - \frac{3}{4} + \frac{2}{3} - \frac{1}{4} + \frac{1}{3}} \right):\frac{5}{{11}}\\
= \left( {\frac{{ - 4}}{4} + \frac{3}{3}} \right).\frac{{11}}{5}\\
= 0\\
b)B = 3:{\left( { - \frac{3}{2}} \right)^2} + \frac{1}{9}.\sqrt {36} \\
= 3.\frac{4}{9} + \frac{1}{9}.6\\
= \frac{4}{3} + \frac{2}{3} = 2\\
8)a) - \frac{2}{3}x + \frac{5}{8} = - \frac{7}{{12}}\\
- \frac{2}{3}x = - \frac{7}{{12}} - \frac{5}{8}\\
- \frac{2}{3}x = - \frac{{29}}{{24}}\\
x = \frac{{29}}{{16}}\\
b){\left( {2x + 3} \right)^2} = 25\\
\Rightarrow \left[ \begin{array}{l}
2x + 3 = 5\\
2x + 3 = - 5
\end{array} \right.\\
\Rightarrow \left[ \begin{array}{l}
x = 1\\
x = - 4
\end{array} \right.
\end{array}$
