Răspuns:
a) x = {0,2,4,14}
b) x = {0,6}
Explicație pas cu pas:
D15 = {1,3,5,15}
x + 1 | 15
x + 1 = 1 => x = 0
x + 1 = 3 => x = 2
x + 1 = 5 => x = 4
x + 1 = 15 => x = 14
x = {0,2,4,14}
D26 = {1, 2, 13, 26}
2x + 1 | 26
2x + 1 = 1 => x = 0
2x + 1 = 2 => x = 1/2 ∉ N
2x + 1 = 13 => x = 6
2x + 1 = 26 => x = 25/2 ∉ N
x = {0,6}