If x = 2+223+213, then x3−6x2+6x =
3
2
1
0
x = 2+223+213 ⇒ x−2 = 223+213
Cubing both sides, we get
x3−8−6x2+12x = 6+6(x−2)
⇒ x3−6x2+6x = 2