Question

Va rog frumos, rezolvati exercitiul 5.Pwp!

Answer 1

2n+3|5n+13/×2
2n+3|2n+3/×5
=>2n+3|2(5n+13)-5(2n+3)
2n+3|10n+26-10n-15
2n+3|11
2n+3 apartine multimii {0,11,22,33,...}/-3
2n apartine {-3,8,19,30,...}/2
n apartine {-3/2,4,19/2,15,..}
n apartine N
=> n apartine {4,15..}