13. Scriem numere in baza 10 si obtinem:
a.
[tex]\frac{10x+y+10y+x}{x+y} =\frac{11x+11y}{x+y} =\frac{11(x+y)}{x+y} =11[/tex]
b.
[tex]\frac{11x+11y}{22} =\frac{11(x+y)}{22}= \frac{x+y}{2}[/tex]
c.
[tex]\frac{100a+10b+c+100b+10c+a+100c+10a+b}{100x+10y+z+100y+10x+z+100z+10x+y} =\frac{111(a+b+c)}{111(x+y+z)} =\frac{(a+b+c)}{(x+y+z)}[/tex]
d.
[tex]\frac{100a+10b+c+100b+10c+a+100c+10a+b}{a+b+b} =\frac{111(a+b+c)}{a+b+c} =111[/tex]
14.
a.
[tex]\frac{n+2+1}{n+2} =1+\frac{1}{n+2} \\\\\frac{1}{n+2} \ ireductibila[/tex]
b.
[tex]\frac{n+4+1}{n+4} =1+\frac{1}{n+4} \\\\\frac{1}{n+4} \ ireductibila[/tex]
c.
[tex]\frac{2(n+3)+1}{n+3} =2+\frac{1}{n+3} \\\\\frac{1}{n+3} \ ireductibila[/tex]
d.
[tex]\frac{2(n+4)+1}{n+4} =2+\frac{1}{n+4} \\\\\frac{1}{n+4} \ ireductibila[/tex]
e.
[tex]\frac{3(n+3)+1}{n+3} =3+\frac{1}{n+3} \\\\\frac{1}{n+3} \ ireductibila[/tex]
f.
[tex]\frac{3(2n+3)+n+1}{2n+3} =3+\frac{n+1}{2(n+1)+1} \\\\\frac{n+1}{2(n+1)+1} \ ireductibila[/tex]
