Đáp án:
Bài `1`
`a,`
`(-17)/30 - 11/(-15) + (-14)/24`
`= 1/6 + (-14)/24`
`= (-5)/12`
`b,`
`(-4)/11 + 5/6 + 7/11 - 5/6`
`= (-4/11 + 7/11) + (5/6 - 5/6)`
`= 3/11 + 0`
`= 3/11`
`c,`
`(-5)/6 × 7/13 + 19/13 ÷ 6/(-5) + 2/5`
`= (-35)/78 + (-95)/78 + 2/5`
`= (-5)/3 + 2/5`
`= (-19)/15`
`d,`
`8/15 + (-13)/30 - 5 1/10`
`= 1/10 - 5 1/10`
`= -4`
`e,`
`1/4 ÷ (10,3 - 9,8) - 3/4`
`= 1/4 ÷ 1/2 - 3/4`
`= 1/2 - 3/4`
`= (-1)/4`
`f,`
`(3 - 2 3/5) × 4 1/6 - 1 3/5 ÷ 1 1/15`
`= (3 -13/5)×25/6 - 8/5 ÷ 16/15`
`= 2/5 × 25/6 - 3/2`
`= 5/3 - 3/2`
`= 1/6`
Bài `2`
`a,`
`3/5x - 2/3 = -1/2`
`-> 3/5x = -1/2 + 2/3`
`-> 3/5x = 1/6`
`-> x = 1/6 ÷ 3/5`
`-> x = 5/18`
Vậy `x = 5/18`
`b,`
`5/6x + 1/3 = 7/12`
`-> 5/6x = 7/12 - 1/3`
`-> 5/6x = 1/4`
`-> x = 1/4 ÷ 5/6`
`-> x = 3/10`
Vậy `x = 3/10`
`c,`
`(1/2 - x) × 2/3 = 1/8`
`-> 1/2 - x = 1/8 ÷ 2/3`
`-> 1/2 - x = 3/16`
`-> x = 1/2 - 3/16`
`-> x = 5/16`
Vậy `x = 5/16`
`d,`
`4/5 - 7/3 = 2 3/5`
`-> (-23)/15 = 13/5` (Vô lí)
`e,`
`|2x - 3| = 5`
`->` \(\left[ \begin{array}{l}2x-3=5\\2x-3=-5\end{array} \right.\)
`->` \(\left[ \begin{array}{l}2x=8\\2x=-2\end{array} \right.\)
`->` \(\left[ \begin{array}{l}x=4\\x=-1\end{array} \right.\)
Vậy `x = 4` hoặc `x = -1`
`f,`
`|x + 2/5| = 1/2`
`->` \(\left[ \begin{array}{l}x + \dfrac{2}{5} = \dfrac{1}{2}\\x+\dfrac{2}{5}=\dfrac{-1}{2}\end{array} \right.\)
`->` \(\left[ \begin{array}{l}x=\dfrac{1}{10}\\x=\dfrac{-9}{10}\end{array} \right.\)
Vậy `x= 1/10` hoặc `x= (-9)/10`
