Question

(2n-1)il divide pe(4n+5)

Answer 1

2n-1|4n+5
2n-1|4n-2+7

(4n-2+7)/(2n-1) ∈N
2+7/(2n-1)∈N
cum 2∈N , ramane ca 7/(2n-1) sa ∈N

adica
2n-1∈D7
2n-1∈{1;7}
2n-1=1...n=1
2n-1=7....n=4
n∈ {1;4}