Question

(x-3).(x+6)>0 alguém sabe???

Answer 1

Aplica distributiva:

(x - 3) . (x + 6) > 0
x² +6x -3x - 18 > 0
x² +3x - 18 > 0 (vamos calcular os possiveis X)

Achando Δ:
Sendo a = 1, b = 3, c = 18

Δ = b² -4.a.c
Δ = 3² -4.1.-18
Δ = 9+72
Δ = 81

Usando baskara:

X = -b+-√Δ/2.a
X = -3+-√81/2.1
X = -3+-9/2
X₁ = -3+9/2
X₁ = 3
X₂ = -3-9/2
X₂ = -6

x² +3x - 18 > 3