(x - 6) (x + 1) < 0;​

(x - 6) (x + 1) < 0;​

(x - 6)< 0;​ =>x < 6

(x + 1) > 0; =>x >- 1; => x∈(-1;6)

или

(x - 6)> 0;​ =>x > 6

(x + 1) < 0;​ => x <- 1; x∈(-∞;-1)∩(6;∞)= ∅

отв x∈(-1;6)