Lời giải:
Câu c)
`-3/5 * 2/7 + -3/7 * 3/5 + (-3/7)`
`=3/5*[-2/7 + (-3/7)]+(-3/7)`
`=3/5* -5/7 + (-3/7)`
`=-3/7+(-3/7)`
`=-6/7`
;
;
Bài 2:
a)
`x+3/22=27/121 * 11/9`
`x+3/22=3/11`
`x=3/11-3/22`
`x=3/22`
;
;
;
b)
`1/5÷x=1/5 - 1/7`
`1/5÷x=2/35`
`x=1/5÷2/35`
`x=7/2`
;
;
;
c)
`|2x-1/2|=3/4`
\(\left[ \begin{array}{l}2x-\dfrac{1}{2}=\dfrac{3}{4}\\2x-\dfrac{1}{2}=-\dfrac{3}{4}\end{array} \right.\)
\(\left[ \begin{array}{l}2x=\dfrac{5}{4}\\2x-\dfrac{1}{4}\end{array} \right.\)
\(\left[ \begin{array}{l}x=\dfrac{8}{5}\\x=-\dfrac{1}{8}\end{array} \right.\)