Bài tập 114 trang 32 SBT Toán 6 Tập 2

Bài tập 114 trang 32 SBT Toán 6 Tập 2

\(\begin{array}{l}
a)0,5x - \frac{2}{3}x = \frac{7}{{12}}\\
\left( {0,5 - \frac{2}{3}} \right)x = \frac{7}{{12}}\\
\left( {\frac{1}{2} - \frac{2}{3}} \right)x = \frac{7}{{12}}\\
x = \frac{7}{{12}}:\frac{{ - 1}}{6}\\
x = \frac{7}{{12}}.\left( { - 6} \right)\\
x = \frac{7}{2}\\
b)x:4\frac{1}{3} =  - 2,5\\
x:\frac{{13}}{3} = \frac{{ - 5}}{2}\\
x = \frac{{ - 5}}{2}.\frac{{13}}{3}\\
x = \frac{{ - 65}}{6}\\
c)5,5x = \frac{{13}}{{15}}\\
\frac{{11}}{2}x = \frac{{13}}{{15}}\\
x = \frac{{13}}{{15}}:\frac{{11}}{2}\\
x = \frac{{13}}{{15}}.\frac{2}{{11}}\\
x = \frac{{26}}{{165}}\\
d)\left( {\frac{{3x}}{7} + 1} \right):\left( { - 4} \right) = \frac{{ - 1}}{{28}}\\
\frac{{3x}}{7} + 1 = \frac{{ - 1}}{{28}}.\left( { - 4} \right)\\
\frac{{3x}}{7} + 1 = \frac{1}{7}\\
\frac{{3x}}{7} = \frac{1}{7} - 1 = \frac{{ - 6}}{7}\\
x = \frac{{ - 6}}{7}:\frac{3}{7}\\
x = \frac{{ - 6}}{7}.\frac{7}{3} =  - 2
\end{array}\)

-- Mod Toán 6