^2 insemna la puterea a 2
E(x)= x(9x^2-12x+4)-2x^2+4x+x^3-4x^2+4x=
9x^3-12x^2+4x-6x^2+8x+x^3= 10x^3-18x^2+12x
E(-a)+E(a)= (-10x^3+18x^2-12x)+(10x^3-18x^2+12x)= 0
