Đáp án :
Câu 1
$a/$ `(|5| - 12 + 2019^0) - (5 - |-12|)`
`= (5 - 12 + 1) - (5 - 12)`
`= 5 - 12 + 1 - 5 + 12`
`= (5 - 5) + (-12 + 12) + 1`
`= 1`
$b/$ `(3/4 - 3/5 - (-11)/20) : 2/5`
`= (3/20 + 11/20) . 5/2`
`= 7/10 . 5/2`
`= 7/4`
$c/$ `1 1/3 - 0,2 . (50% - 5/6) + (-1/3)^2`
`= 4/3 - 2/10 . (-1)/3 + 1/9`
`= 4/3 + 1/15 + 1/9`
`= 7/5 + 1/9`
`= 68/45`
Câu 2
$a/$ `x - 1/4 = 2/3`
`-> x = 11/12`
$b/$ `2 - |3/4 - x| = 7/12`
`-> |3/4-x| = 17/12`
`-> 3/4-x = 17/12` hoặc `3/4-x = (-17)/12`
`-> x = (-2)/3` hoặc `x = 13/6`
$c/$ `(x + 3)/(-15) = 1/3`
`-> x + 3 = -15 . 1/3`
`-> x + 3 = -5`
`-> x = -8`
