Question

. Решите уравнение: 1) (2x + 3) - 4(x - 1)(x + 1) = 49 2) (3x + 4) -(3x - 1) (1 + 3x) = 49 3) x + 2x2 – 9x - 18 = 0; 4) у- 3у2 - 4 y + 12 = 0. x​

Answer 1

Объяснение:

1. (2х+3)-4(х^2-1) = 2х+3-4х^2+4 = -4х^2+2х+7 = 49

4х^2 - 2х + 42 = 2х^2 - х + 21 = 0

D = 1-4*2*21 < 0 => нет корней

2. (3х+4)-(9х^2-1) = -9х^2+3х+5 = 49

9х^2 - 3х + 44 = 0

D = 9-4*9*44 < 0 => нет корней

3. 2х^2-8х-18 = х^2-4х-9 = 0

D = 4*4 + 4*9 = 4*(4+9) = 4*13

х1 = (4-2√13)/2 = 2-√13

х2 = (4+2√13)/2 = 2+√13

4. 3у^2+3у-12 = у^2+у-4 = 0

D = 1 + 4*4 = 17

x1 = (-1-√17)/2

x2 = (-1+√17)/2