3х²-2х-1 = 0

а = 3, b = -2, c = -1

D = b²-4ac = (-2)²-4×3×(-1) = 4+12 = 16

Первый x = (-b-√D)/2a = (2-4)/6 = -2/6 = -1/3

Второй х = (-b+√D)/2a = (2+4)/6 = 1

Сумма корней = -1/3+1 = 2/3

Произведение корней = -1/3×1 = -1/3