Odpowiedź:
IIx - 7I - 4I = 3
Ix - 7I - 4 = 3 ∨ Ix - 7I - 4 = - 3
Ix - 7I = 3 + 4 ∨ Ix - 7I = - 3 + 4
Ix - 7I = 7 ∨ Ix - 7I =1
x - 7 =7 ∨ x - 7 = - 7 ∨ x - 7 = 1 ∨ x - 7 = - 1
x = 7 + 7 ∨ x = - 7 + 7 ∨ x = 1 + 7 ∨ x = - 1 + 7
x = 14 ∨ x = 0 ∨ x = 8 ∨ x = 6
∨ - znaczy "lub"
