Tìm x: a) 8x^3 – 12x^2 + 6x – 1 = 0; b) (4x – 3)^2 – 3x(3 – 4x) = 0.
Giải thích
a) 8x3 – 12x2 + 6x – 1 = 0
⇔(2x)3 – 3.(2x)2.1 + 3. 2x. 12 - 13 = 0
⇔(2x – 1)3 = 0
⇔2x – 1 = 0
⇔x=12.
Vậy x=12.
b)
(4x – 3)2 – 3x(3 – 4x) = 0
⇔(4x – 3)2 + 3x(4x – 3) = 0
⇔(4x – 3)(4x – 3 + 3x) = 0
⇔(4x – 3)(7x – 3) = 0
⇔4x−3=07x−3=0
⇔x=34x=37
Vậy x=34 hoặc x=37.