Question

log 0.7 ( x2-4x-5)=log 0.7 (7-3x)

Answer 1

Ответ:

x₁=4, x₂=-3

Объяснение:

х² - 4х - 5 = 7 - 3х

х² - 4х - 5 - 7 + 3х = 0

х² - х - 12 = 0

D = b² - 4ac

D = (-1)² - 4*1*(-12) = 49

$x_{1,2} =\frac{-b+-\sqrt{D}}{2a}$

$x_{1} =\frac{1+7}{2} =4\\\\x_{2}=\frac{1-7}{2} =-3$