Đáp án:
`a) x =` `5/3`
`b) x =` `(-1)/9`
`c) x ∈` { `3/8` ; `(-1)/8` }
`d) x =` `5/3`
Giải thích các bước giải:
`a) x +` `1/3` `= 2`
`=> x = 2 -` `1/3`
`=> x =` `6/3` `-` `1/3`
`=> x =` `5/3`
Vậy x `=` `5/3`
`b)` `1/2` `-` `1/2` `: x = 5`
`=>` `1/2` `: x =` `1/2` `- 5 `
`=>` `1/2` `: x =` `1/2` - `10/2`
`=>` `1/2` `: x =` `(-9)/2`
`=> x =` `1/2` `:` `(-9)/2`
`=> x =` `1/2` . `(-2)/9`
`=> x =` `(-1)/9`
Vậy `x =` `(-1)/9`
`c)` | 2x - `1/4` | `=` `1/2`
Trường hợp `1 :` `2x -` `1/4` `=` `1/2`
`=> 2x =` `1/2` `+` `1/4`
`=> 2x =` `2/4` `+` `1/4`
`=> 2x =` `3/4`
`=> x =` `3/4` `: 2`
`=> x =` `3/4` . `1/2`
`=> x =` `3/8`
Trường hợp `2 :` `2x -` `1/4` `=` `(-1)/2`
`=> 2x =` `(-1)/2` `+` `1/4`
`=> 2x =` `(-2)/4` `+` `1/4`
`=> 2x =` `(-1)/4`
`=> x =` `(-1)/8`
Vậy `x ∈` { `3/8` ; `(-1)/8` }
`d) ( x - 1 )³ =` `8/27`
`=> ( x - 1 )³ =` ( `2/3`)`³`
`=> x - 1 =` `2/3`
`=> x =` `2/3` `+ 1`
`=> x =` `2/3` `+` `3/3`
`=> x =` `5/3`
Vậy `x =` `5/3`
