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1) (2x-1)³ = 8/27
Giải: Lập phương hai vế.
=> 2x - 1 = (8/27)^(1/3)
=> 2x - 1 = 2/3
=> 2x = 2/3 + 1 = 5/3
=> x = 5/6.

2) (2x-1)³ = 1/4
=> 2x - 1 = (1/4)^(1/3)
=> 2x - 1 = 1/2
=> 2x = 1/2 + 1 = 3/2
=> x = 3/4.

3) (2-3x)² = 9/4
=> 2 - 3x = ±(3/2)
Xét trường hợp:
- 2 - 3x = 3/2
=> -3x = 3/2 - 2 => -3x = -1/2 => x = 1/6.
- 2 - 3x = -3/2
=> -3x = -3/2 - 2 => -3x = -7/2 => x = 7/6.

4) (2x+1)² = 16/25
=> 2x + 1 = ±(4/5)
Xét trường hợp:
- 2x + 1 = 4/5
=> 2x = 4/5 - 1 => 2x = -1/5 => x = -1/10.
- 2x + 1 = -4/5
=> 2x = -4/5 - 1 => 2x = -9/5 => x = -9/10.

5) (5x+1)² = 36/49
=> 5x + 1 = ±(6/7)
Xét trường hợp:
- 5x + 1 = 6/7
=> 5x = 6/7 - 1 => 5x = -1/7 => x = -1/35.
- 5x + 1 = -6/7
=> 5x = -6/7 - 1 => 5x = -13/7 => x = -13/35.

6) (3x-4)² = (-3/4)²
=> 3x - 4 = ±(3/4)
Xét trường hợp:
- 3x - 4 = 3/4
=> 3x = 3/4 + 4 => 3x = 19/4 => x = 19/12.
- 3x - 4 = -3/4
=> 3x = -3/4 + 4 => 3x = 13/4 => x = 13/12.

7) (1 - 2/3x)² = 4/9
=> 1 - 2/3x = ±(2/3)
Xét trường hợp:
- 1 - 2/3x = 2/3
=> -2/3x = 2/3 - 1 => -2/3x = -1/3 => x = 1.
- 1 - 2/3x = -2/3
=> -2/3x = -2/3 - 1 => -2/3x = -5/3 => x = 5/2.

8) (3/4 - 7x)² = 1
=> 3/4 - 7x = ±1
Xét trường hợp:
- 3/4 - 7x = 1
=> -7x = 1 - 3/4 => -7x = 1/4 => x = -1/28.
- 3/4 - 7x = -1
=> -7x = -1 - 3/4 => -7x = -7/4 => x = 1/4.

9) (4/7 - 2/x)² = 4/9
=> 4/7 - 2/x = ±(2/3)
Xét trường hợp:
- 4/7 - 2/x = 2/3
=> -2/x = 2/3 - 4/7
=> -2/x = 14/21 - 12/21 = 2/21 => x = -21.
- 4/7 - 2/x = -2/3
=> -2/x = -2/3 - 4/7
=> -2/x = -14/21 + 12/21 = -2/21 => x = 21.

10) (x - 1/2)³ = 81
=> x - 1/2 = 81^(1/3)
=> x - 1/2 = 4.326 => x = 4.826.

11) (x + 1)³ = -27/4
=> x + 1 = (-27/4)^(1/3)
=> x + 1 = -3/2 => x = -5/2.

12) (x + 1/2)³ = -1/81
=> x + 1/2 = (-1/81)^(1/3)
=> x + 1/2 = -1/3 => x = -5/6.

13) (2/3 - x)² = 4/9
=> 2/3 - x = ±(2/3)
Xét trường hợp:
- 2/3 - x = 2/3 => x = 0.
- 2/3 - x = -2/3 => x = 4/3.

14) (2/5 - 3x)² = 3/5 - 4/25
Giải: 3/5 = 15/25 => 3/5 - 4/25 = 11/25
=> (2/5 - 3x)² = 11/25
=> 2/5 - 3x = ±(√11/5)
Xét trường hợp:
- 2/5 - 3x = √11/5
=> 3x = 2/5 - √11/5 => x = (2 - √11)/15.
- 2/5 - 3x = -√11/5
=> 3x = 2/5 + √11/5 => x = (2 + √11)/15.

15) (2/5 - 3)² = 1/5 - 4/25
Giải: 4/25 = 4/25 => (2/5 - 3)² = 0
=> 2/5 - 3 = 0 => 3 = 2/5.

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