Đáp án:
\(\begin{array}{l}
B3:\\
a. - \frac{5}{2} < a < \frac{5}{2}\\
b.50\%
\end{array}\)
Giải thích các bước giải:
\(\begin{array}{l}
B1:\\
a.\frac{4}{5} + \frac{1}{5} - \frac{3}{2} = 1 - \frac{3}{2} = - \frac{1}{2}\\
b.\frac{{10}}{{13}} + \frac{{15}}{{91}} - \frac{{50}}{{91}}\\
= \frac{{10}}{{13}} - \frac{5}{{13}} = \frac{5}{{13}}\\
c.1 - \frac{1}{2} + \frac{1}{2} - \frac{1}{3} + ... + \frac{1}{5} - \frac{1}{6}\\
= 1 - \frac{1}{6} = \frac{5}{6}\\
B3:\\
a.\left\{ \begin{array}{l}
\frac{{ - 8 + 3}}{{12}} < \frac{{2a}}{{12}}\\
\frac{{2a}}{{12}} < \frac{{9 - 4}}{{12}}
\end{array} \right.\\
\to \left\{ \begin{array}{l}
- 5 < 2a\\
2a < 5
\end{array} \right.\\
\to - \frac{5}{2} < a < \frac{5}{2}\\
b.0,6m = 60cm\\
\to \% = \frac{{30}}{{60}}.100 = 50\%
\end{array}\)
