Răspuns:
a)
(2n+5 ):2= c rest 1
n=0 5:2= 2rest 1 n= 1 7:2= 3 rest 1
n=2 9:2= 4 rest 1 n=3 11:2=5 rest 1
n=10 25:2= 12 rest 1 deci oricare ar fi n restul va fi 1
b) 2n+5= 2009 2n= 2009-5= 2004
2n=2004 n=2004:2= 1002 n= 1002
c) 1003 valori ( de la 0 la 1002)
