Cộng các phân số sau
a) \(\frac{1}{6} + \frac{2}{5}\)
b) \(\frac{3}{5} + \frac{{ - 7}}{4}\)
c) \(\left( { - 2} \right) + \frac{{ - 5}}{8}\)
a)
\(\begin{array}{l}
\frac{1}{6} + \frac{2}{5} = \frac{5}{{30}} + \frac{{12}}{{30}}\\
= \frac{{5 + 12}}{{30}} = \frac{{17}}{{30}}
\end{array}\)
b)
\(\begin{array}{l}
\frac{3}{5} + \frac{{ - 7}}{4} = \frac{{12}}{{20}} + \frac{{ - 35}}{{20}}\\
= \frac{{12 + \left( { - 35} \right)}}{{20}} = \frac{{ - 23}}{{20}}
\end{array}\)
c)
\(\begin{array}{l}
\left( { - 2} \right) + \frac{{ - 5}}{8} = \frac{{ - 16}}{8} + \frac{{ - 5}}{8}\\
= \frac{{ - 16 + \left( { - 5} \right)}}{8} = \frac{{ - 21}}{8}
\end{array}\)
-- Mod Toán 6
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