Câu `2 :`

`a ) ( -0,25 ) . 40 + 3`

`= -10 + 3`

`= -7`

`c ) [ ( 2/3 - 1/4 ) + ( -2 )^2 . 3 ] - 1`

`= [ 5/12 + 4 . 3 ] - 1`

`= [ 5/12 + 12 ] - 1`

`= 149/12 - 1`

`= 137/12`

Câu `3 :`

`b ) 2 . ( x - 1 ) = 3^3 - 1`

`2 . ( x - 1 ) = 27 - 1`

`2 . ( x - 1 ) = 26`

`x - 1 = 26 : 2`

`x - 1 = 13`

`x = 13 + 1`

`x = 14`

Vậy `x = 14`

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