a) xdivide 12 x=1,2,3,4,6,12
A={1,2,3,4,6,12}
b)x+1 divide 1=> x=0
B={0}
(n+5)/n=n/n+5/n=1+5/n.Acest numar e natural daca 5/n este numar natural adica n divizor al lui 5
n={1,5]
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18) (n+5)/n=n/n+5/n=1+5/n Acest numar este natural daca
5/n =nr natural=> n=1sau 5
c)x+3 divide 3
x+3=1 nu are solutii in N
x+3=3=> x=0
C+{0}
d)X+2 divide 6
x+2={1,2,3,6}
x+2=1 imposibil
x+2=2=> x=0
x+2=3 =>x=3-2=1
x+2 =6 x=6-2=4
