Đáp án:
`a,`
`2/9 - 7/8x = 1/3`
`-> 7/8x = 2/9 - 1/3`
`-> 7/8x = -1/9`
`-> x = -1/9 ÷ 7/8`
`-> x = -8/63`
`text{Vậy}` `x = -8/63`
`b,`
`2/3x - 3/2 (x - 1/2) = 5/12`
`-> 2/3x - 3/2x + 3/4 = 5/12`
`-> -5/6x = 5/12 - 3/4`
`-> -5/6x = -1/3`
`-> x = -1/3 ÷ (-5/6)`
`-> x = 2/5`
`text{Vậy}` `x = 2/5`
`c,`
`-1 2/3 - |2x - 1| ÷ 3/5 = -2`
`-> -5/3 - |2x - 1| ÷ 3/5 = -2`
`-> |2x - 1| ÷ 3/5= -5/3 - (-2)`
`-> |2x - 1| ÷ 3/5 = 1/3`
`-> |2x - 1| = 1/3 × 3/5`
`-> |2x - 1| = 1/5`
`->` \(\left[ \begin{array}{l}2x-1=\dfrac{1}{5}\\2x-1=\dfrac{-1}{5}\end{array} \right.\)
`->` \(\left[ \begin{array}{l}2x=\dfrac{6}{5}\\2x=\dfrac{4}{5}\end{array} \right.\)
`->` \(\left[ \begin{array}{l}x=\dfrac{3}{5}\\x=\dfrac{2}{5}\end{array} \right.\)
`text{Vậy}` `x ∈ {3/5; 2/5}`
`d,`
`(x - 7)/36 = 4/(x - 7)`
`-> (x - 7) × (x- 7 ) = 36 × 4`
`-> (x - 7)^2 = 144`
`->` \(\left[ \begin{array}{l}(x-7)^2=12^2\\(x-7)^2=(-12)^2\end{array} \right.\)
`->` \(\left[ \begin{array}{l}x-7=12\\x-7=-12\end{array} \right.\)
`->` \(\left[ \begin{array}{l}x=19\\x=-5\end{array} \right.\)
`text{Vậy}` `x ∈ {19;-5}`
