Question

Determinati multimea A

Answer 1

3x+1/2x-5 ∈Z
⇒3x+1 | 2x-5⇒  3x+1 | 6x-15
3x+1 | 3x+1⇒ 3x+1 | 6x+2
(le scadem) ⇒ 3x+1 | 17
3x+1 ∈{-17,-1,1,17}
3x∈ { -18,-2,0,16}
x∈ {-6, -2/3, 0, 16/3}
x∈Z
⇒x∈ {-6,0}