EQUAÇÕES POLINOMIAIS - FGV 1995

Solution to the question whose statement is: "(FGV − 1995) Regarding the roots of 2x³ − x² − 2x + 1 = 0, it is true that (A) none of them are real. (B) exactly two of them are negative. (C) only one of them is irrational. (D) all three are integers. (E) they belong to the interval [−1,1]."