Đáp án :
Câu 1
$a/$ `5 . 2/15 - 1/2`
`= 2/3 - 1/2`
`= 1/6`
$b/$ `2/7 . 5/3+ 2/7 . (-15)/3 - 5/7 . 10/3`
`= 2/7 . (5/3 + (-15)/3) - 5/7 . 10/3`
`= 2/7 . (-10)/3 - 5/7 . 10/3`
`= 10/3 . ( (-2)/7 - 5/7)`
`= 10/3 . (-1)`
`= (-10)/3`
$c/$ `(1/3 + 3/4 - 13/12) : (12/23 + 123/234 + 1234/2345)`
`= (13/12 - 13/12) : (12/23 + 123/234 + 1234/2345)`
`= 0 : (12/23 + 123/234 + 1234/2345)`
`= 0`
Câu 2
$a/$ `x - 3/4 = 1 1/2`
`-> x - 3/4 = 3/2`
`-> x = 9/4`
$b/$ `|3/4x - 1| - 1/2 = 4`
`-> |3/4x - 1| = 9/2`
`-> 3/4x - 1 = 9/2` hoặc `3/4x - 1= (-9)/2`
`-> 3/4x = 11/2` hoặc `3/4x = (-7)/2`
`-> x = 22/3` hoặc `x = (-14)/3`
$c/$ `(2x - 1/2) (3/4 + 3x) = 0`
`-> 2x - 1/2 = 0` hoặc `3/4 + 3x = 0`
`-> 2x = 1/2` hoặc `3x = (-3)/4`
`-> x = 1/4` hoặc `x = (-1)/4`
