Question

D={x=N|15/2x+1=N}

Repede va rog. Dau coroana​

Answer 1

D = {x ∈ ℕ| 15/(2x+1) ∈ ℕ}

2x+1 ∈ D₁₅ ⇔ 2x+1 ∈ {1,3,5,15} |-1

⇔ 2x ∈ {0,2,4,14} |:2 ⇔ x ∈ {0,1,2,7}

⇒ D = {0,1,2,7}.