Bài `5` `:`
`1) 156 - ( x + 61 ) = 82`
`=> ( x + 61 ) = 156 - 82`
`=> x = 74 - 61`
`=> x = 13`
Vậy `x = 13`
`2) 134 : ( x - 3 ) = 35 + 160 : 5`
`134 : ( x - 3 ) = 35 + 32`
`134 : ( x - 3 ) = 67`
`=> x - 3 = 134 : 67`
`=> x - 3 = 2`
`=> x = 5`
Vậy `x = 5`
`3) ( 2x - 1 )³ = 125`
`=> ( 2x - 1 )³ = 5³`
`=> 2x - 1 = 5`
`=> 2x = 6`
`=> x = 3`
Vậy `x = 3`
4) $3^{x + 2}$ `- 2 .` $3^{x}$ `= 189`
`=>` $3^{x}$ . `3²` `- 2 .` $3^{x}$ `= 189`
`=>` $3^{x}$ . ( 9 - 2 ) `= 189`
`=>` $3^{x}$ `. 7 = 189`
`=>` $3^{x}$ `= 27`
`=>` $3^{x}$ `= 3³`
`=> x = 3`
Vậy `x = 3`
