Question

determine o valor do x (X-4) . ( X +2) >0​

Answer 1

Olá!

(X-4).(X+2)

X^2 + 2X - 4X -8 > 0
X^2 -2X -8 > 0

a = 1
b = -2
c = -8

Δ= b^2 - 4.a.c
Δ= -2^2 - 4.1.(-8)
Δ= 4 + 32
Δ= 36

X= -b+/-√Δ/2.a
X= -(-2)+/-6/2.1
X= 4 +/- 6 / 2

X1= 10/2 = 5
X2= -4/2 = -2