Question

A={x apartine N stelat|2x+1 divide 30}

Answer 1

2x+1 / 30 ⇒ 2x+1 ∈ D30⇒ 2x+1 ∈ {1,2,3,5,6,10,15,30}
⇒ 2x ∈ {0,1,2,4,5,9,14,29} ⇒ x∈ {0,1,2,7}⇒ A = {0,1,2,7}