Question

sa se determine n€N daca 9/2n+1 este supraunirara.......

3/2n+1€N

Answer 1

   
a)
9 / (2n + 1) > 1;  n ∈ N
2n + 1 < 9
2n < 9 - 1
2n < 8
n < 8 / 2
n < 4
n ∈ {0; 1; 2}

b)
3 / (2n + 1) ∈ N;  n ∈ N
D3 = {1; 3}
2n + 1 = 1
2n = 1 - 1
2n = 0
n = 0
2n + 1 = 3
2n = 3 - 1
2n = 2
2n = 2 / 2
 n = 1
n ∈ {0; 1}