Đáp án+Giải thích các bước giải:
`d)`
`(-2)^3 + (75% - 0,25) : ( 2 1/4 - 1 5/6)`
`= (-8) + (3/4 - 1/4) : (9/4 - 11/6)`
`= (-8) + 2/4 : (27/12 - 22/12)`
`= (-8) + 1/2 : 5/12`
`= (-8) + 1/2 . 12/5`
`= (-8) + 12/10`
`= -8 + 6/5`
`= (-40)/5 + 6/5`
`= -34/5`
$\\$
`b)`
`(1/3)^(2x-1) - (1/3)^2 = (-2)/27`
`(1/3)^(2x-1) - 1/9 = (-2)/27`
`(1/3)^(2x-1) = (-2)/27 + 1/9`
`(1/3)^(2x-1) = (-2)/27 + 3/27`
`(1/3)^(2x-1) = 1/27`
`(1/3)^(2x-1) = (1/3)^3`
`-> 2x-1 = 3`
`2x = 3+1`
`2x = 4`
`x = 4:2`
`x = 2`
Vậy `x = 2`
