a³ - b³ = ( a -b) · ( a² + ab + b² 0
| ( x +1 - x + 2) · [( x +1)² + ( x +1)· ( x -2) + ( x - 2)² ] | = 9
= 3
3 | x² + 2x + 1 + x² +x - 2x - 2 + x² - 4x + 4 | = 9 impartim cu 3
| 3x² -3x + 3| = 3 impartim cu 3
|x² - x + 1 | = 1
daca x² - x + 1 =1 x² - x + 1 = -1
x² -x = 0 x² - x +2= 0
x(x -1) = 0 Δ = 1 - 4 ·1·2 = 1- 8 = - 7 <0
x =0 ecuatia nu are solutii intregi
x = 1
S = { 0 ; 1}
