Question

A= { x + 12 ; 2x-3; 3x+5}
B= { 2x +1 ; x + 8 ; 5x - 17 }
 Aflati x∈ |N astfel incat B=A

Answer 1

2x+1=x+12, x=11
x+8=2x-3, 9=x, adica x=9
5x-17=3x+5, 2x=5+17, 2x=22, x=11

Answer 2

daca multimea A = multimea B, atunci ⇒
1) x +12 = 2x + 1 ⇔ x - 2x = 1 -12 ⇔ - x = - 11 I · ( - 1)
    x = 11
2) 2x  - 3 = x + 8 ⇔ 2x - x = 8 + 3 ⇔ x = 11
   x = 11
3) 3x + 5 = 5x -17 ⇔ 3x - 5x = - 17 - 5 ⇔ - 2x = - 22 I ·( - 1)
   2x = 22 ⇔ x = 22/2 ⇔ x = 11
   x = 11