Câu 1:
a) $\frac{-5}{3}$ +$\frac{1}{6}$ =$\frac{-10+1}{6}$ = $\frac{-9}{6}$
b) $\frac{-7}{8}$- $\frac{-3}{10}$= $\frac{5}{7}$+ $\frac{2}{7}$x-$\frac{14}{3}$
c) $\frac{5}{7}$+( $\frac{2}{7}$x- $\frac{14}{3}$ ) =$\frac{5}{7}$-$\frac{4}{3}$= $\frac{-13}{21}$
Câu 2:
a)$A=\frac{11}{12}+ \frac{9}{7}+ \frac{1}{12}- \frac{2}{7}= (\frac{11}{12}+ \frac{1}{12})+( \frac{9}{7}+ \frac{-2}{7})=1+1=2 $
b) $B=-\frac49.\frac73-\frac73.\frac59=\frac73.(\frac49+\frac59)=\frac73.1=\frac73$
c) $C=(\frac14-\frac56)^2=(\frac3{12}-\frac{10}{12})^2=(\frac{-7}{12})^2=\frac{(-7)^2}{12^2}=\frac{49}{144}$
Câu 3:
1/ $x-\frac2{15}=-\frac43 \\
\Leftrightarrow x=-\frac43+\frac2{15}=-\frac65$
2/ $\frac32-x=\frac12 \
\Leftrightarrow x=\frac32-\frac12=1$
3/ $\frac53-\frac23:x=\frac{-1}6 \\
\Leftrightarrow 1:x=\frac{-1}6 \\
\Leftrightarrow x=1:\frac{-1}6=-6$
4/ $|x+\frac15|=0,4=\frac25 \\
\Leftrightarrow \left[\begin{matrix}
x+\frac15=\frac25 & \\
x+\frac15=-\frac25 &
\end{matrix}\right. \\
\\
\Leftrightarrow x=\frac15; x=-\frac35
$
5/
$(x-\frac12)^2=\frac1{16} \\
\Leftrightarrow \left[\begin{matrix}
x-\frac12=\frac14 & \\
x-\frac12=-\frac14 &
\end{matrix}\right. \\
\Leftrightarrow x=\frac34;x=\frac14$
