Question

giúp em b4 ạ 

Answer 1

`3x^3 -5x^2 +11x-6=0`

`<=>3x^3 -2x^2 -3x^2 + 2x+9x-6=0`

`<=>(3x-2)(x^2 -x+3)=0`

`<=>(3x-2)[(x-1/2)^2+11/4]=0`

  Mà `(x-1/2)^2+11/4 > 0`

  `=>3x-2=0`

`<=>x=2/3`

Answer 2

Bài 4

3x³ - 5x² + 11x - 6 = 0

⇔ 3x³ - 2x² - 3x² + 2x + 9x - 6 = 0

⇔ (3x³ - 2x²) - (3x² - 2x) + (9x - 6) = 0

⇔ x²(3x - 2) - x(3x - 2) + 3(3x - 2) = 0

⇔ (3x - 2)(x² - x + 3) = 0

⇔ 3x - 2 = 0 (vì x² - x + 3 > 0 với mọi x)

⇔ 3x = 2

⇔ x = 2/3

Vậy S = {2/3}