Question

cum calculăm 21 supra 3n +1 va rog

Answer 1

3n+1∈D21=(-1+1,-3+3,-7,+7,-21+21)
3n+1=-1⇒3n=-1-1⇒3n=-2⇒n=-2/3
3n+1=1⇒3n=1-1⇒3n=0⇒n=0/3=0
3n+1=-3⇒3n=-3-1⇒3n=-4⇒n=-4/3
3n+1=3⇒3n=3-1⇒3n=2⇒n=2/3
3n+1=-7⇒3n=-7-1⇒3n=-8⇒n=-8/3
3n+1=7⇒3n=7-1⇒3n=6⇒n=6/3⇒n=2
3n+1=-21⇒3n=-21-1⇒3n=-22⇒n=-22/3
3n+1=21⇒3n=21-1⇒3n=20⇒n=20/3  Daca n este numar natural atunci ia decat valorile:0 si 2

Answer 2

21 supra 3 plus 1 egal cu 8