Question

Решите уравнение (x+6)(2x+6)-20=0​

Answer 1

( х + 6 ) ( 2х + 6 ) - 20 = 0

2х2 + 6х + 12х + 36 - 20 = 0

2х2 + 18х + 18 = 0

х1 + х2 = -9

х1х2 = 9

х1 = -7.85

х2 = -1.15

х2 =

Answer 2

Ответ:

x₁ = -8 ;       x₂= -1

Пошаговое объяснение:

(x+6)(2x+6)-20=0​

2x² + 18x + 36 - 20 = 0

2x² + 18x + 16 = 0

x² + 9x + 8 = 0

D = b² - 4ac = 9² - 4*1 *8 = 81 - 32 = 49 = 7²

x₁ = (-b - √d)/2a = (-9 - 7)/2 = -16/2 = -8

x₂ = (-b +√d)/2a = (-9 + 7)/2 = -2/2 = -1