Verified answer

f(x) = - 4x + 16

a) f(x) < 0

- 4x + 16 < 0

- 4x < - 16

x > 4

Otvet : f(x) < 0  при x ∈ (4 ; + ∞)  

б) f(x) = 0

- 4x + 16 = 0

- 4x = - 16

x = 4

Ответ : x = 4 - нуль функции