a) 6 ⋮ x
⇒ x ∈ Ư(6) = {-6; -3; -2; -1; 1; 2; 3; 6}
b) 8 ⋮ (x + 1)
⇒ x + 1 ∈ Ư(8) ={-8; -4; -2; -1; 1; 2; 4; 8}
⇒ x ∈ {-9; -5; -3; -2; 0; 1; 3; 7}
Vì 6⋮ x
=> x ϵ { 1,2,3,6,-1,-2,-3,-6}
Vì 8 ⋮ x +1
=> x+1 ϵ { 1,2,4,8,-1,-2,-4,-8}
=> x ϵ {0,1,3,7,-2,-3,-5,-9}
=> x = -2