a)14/n∈N⇒n∈[tex] D_{14} ={1,2,7,14}[/tex]
b)-10/n∈N⇒n∈divizorilor negativi ai lui 10={-10,-5,-1}, dar n∈N⇒n∈Ф
c)15/(4-k)∈N⇒(4-k)∈[tex] D_{15} ={1,3,5,15}[/tex] I-4
-k∈{-3,-1,4,11} I*(-1)
k∈{3,1,-4,-11}
k∈N⇒k∈{1,3}
d)(2k+1)∈[tex] D_{16} ={1,2,4,8,16}[/tex] I-1
2k∈{0,1,3,7,15} I:2
k∈{0} ( restul nu sunt nr laturale)
e)6/(n+2)∈Z⇒(n+2)∈ [tex] D_{6} ={-6,-3,-2,-1,1,2,3,6}[/tex]} I-2
n∈{-8,-5,-4,-3,-1,0,1,4}
f) 8/(3-n)∈Z⇒(3-n) ∈ [tex] D_{8} ={-8,-4,-2,-1,1,2,4,8}
[/tex]} I-3
-n∈{-11,-7,-5,-4,-2,-1,1,5} I*(-1)
n∈{11,7,5,4,2,1,-1,-5}
n∈N⇒n∈{1,2,4,5,7,11}