3x² + 4x - 4.

By splitting the middle term

3x³ + 4x - 4 = 0

3x² + (6x - 2x) - 4 = 0

3x² + 6x - 2x - 4 = 0

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

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

⇒ x = - 2, 2/3

Verification:

Sum of the zeroes = - (coefficient of x) ÷ coefficient of x²

α + β = - b/a

- 2 + (2/3) = - (4)/3

= - 4/3 = - 4/3

Product of the zeroes = constant term ÷ coefficient of x²

α β = c/a

Product of the zeroes = (- 2) (2/3) = - 4/3