Răspuns :
Răspuns:
(1a + a1 + 1b + b1) =
10 + a + 10a + 1 + 10 + b + 10b + 1 =
11a + 11b + 22 =
11 x (a + b + 2) ⇒ se divide cu (a + b + 2)
1a = 10 + a
a1 = 10a + 1
1b = 10 + b
b1 = 10b + 1
[tex]\it n=\overline{1a}+\overline{a1}+\overline{1b}+\overline{b1}=10+a+10a+1+10+b+10b+1=\\ \\ =11a+11b+22=11\cdot(a+b+2) \Rightarrow (a+b+2)\ este\ un\ divizor\ al\ lui\ n,\\ \\ deci\ \ n\ \vdots\ (a+b+2)[/tex]