[tex] \frac{5}{2n+1} = y [/tex], y∈ℕ
5 = y(2n+1)=> 2n+1 = [tex] \frac{5}{y} [/tex] => 2n = [tex] \frac{5}{y} -1[/tex] =>
=>[tex]n= \frac{5-y}{2y} [/tex]
Sa vedem cum creste sau scade numarul dand valori lui y:
y = 1 => n = (5-1):2 = 2
y = 2 => n = (5-2):4 = [tex] \frac{3}{4} [/tex]
y = 3 => n = (5-3):6 = 2:6 = [tex] \frac{1}{3} [/tex]
y = 4 => n = [tex] \frac{1}{4} [/tex]
y = 5=> n = 0.
y = 6 => (5-6):12= -1/12
=> [tex]n= \frac{5-y}{2y} [/tex] , y∈ℕ
n∈{2 ; 3/4 ; 1/3 ; 1/4; 0 ; -1/12....... -∞}
