1.

3х² - х - 9 = 0,

Д = (-1)² - 4*3*(-9) = 1 + 108 = 109,

2 корня,

11х² + х + 9 = 0

Д = 1² - 4*11*9 = 1 - 396 = -395,

корней нет,

49х² - 28х + 4 = 0,

Д = (-28)² - 4*49*4 = 784 - 784 = 0,

1 корень,

2.

3х² - 9х - 30 = 0,

Д = (-9)² - 4*3*(-30) = 81 + 360 = 441,

х1 = (9 + 21) / 2*3 = 30/6 = 5,

х2 = (9 - 21) / 2*3 = -12/6 = -2,

х² - 9х + 20 = 0

Д = (-9)² - 4*1*20 = 81 - 80 = 1,

х1 = (9 + 1) / 2*1 = 10/2 = 5,

х2 = (9 - 1) / 2*1 = 8/2 = 4,

х² - х - 2 = 0,

Д = (-1)² - 4*1*(-2) = 1 + 8 = 9,

х1 = (1 + 3) / 2*1 = 4/2 = 2,

х2 = (1 - 3) / 2*1 = -2/2 = -1,

х² - 9х + 8 = 0,

Д = (-9)² - 4*1*8 = 81 - 32 = 49,

х1 = (9 + 7) / 2*1 = 16/2 = 8,

х2 = (9 - 7) / 2*1 = 2/2 = 1