a 3X - 17 = 28 b 2 x (X + 6) + 12 = 72 c (X - 140 ):7=3 MŨ 3 - 2 MŨ 3 x 3 d 3 mũ x+1 + 3 mũ x+2 =324

`a, 3x - 17 = 28`

  `3x = 28 + 17`

  `3x = 45`

  `x = 45 : 3`

  `x = 15`

Vậy `x = 15`

`b, 2 xx (x + 6) + 12 = 72`

  `2 xx (x + 6) = 72 - 12`

  `2 xx (x + 6) = 60`

  `x + 6 = 60 : 2`

  `x + 6 = 30`

  `x = 30 - 6`

  `x = 24`

Vậy `x = 24`

`c, (x - 140) : 7 = 3^3 - 2^3 xx 3`

  `(x - 140) : 7 = 27 - 8 xx 3`

  `(x - 140) : 7 = 27 - 24`

  `(x - 140) : 7 = 3`

  `x - 140 = 3 xx 7`

  `x - 140 = 21`

  `x = 21 + 140`

  `x = 161`

Vậy `x = 161`

`d, 3^{x + 1} + 3^{x + 2} = 324`

  `3^x · 3^1 + 3^x · 3^2 = 324`

  `3^x · 3 + 3^x · 9 = 324`

  `3^x · (3 + 9) = 324`

  `3^x · 12 = 324`

  `3^x = 324 : 12`

  `3^x = 27`

  `3^x = 3^3`

  `x = 3`

Vậy `x = 3`