folosim formulele de calcul prescurtat
(a-b)³=a³-3a²b+3ab²-b³
F(x)=64x³-12x²+12x-1-(4x²+4x+1)=
64x³-12x²+12x-1-4x²-4x-1=64x³-16x²+8x-2=2(32x³-8x²+4x-1)
4x³-8x²+4x=4x(2x²-4x+1)
x₁=0
2x²-4x+1=0
Δ=16-8=8
x₂=(4-2√2)/4=2(2-√2)/4=(2-√2)/2
x₃=(4+2√2)/4=2(2+2√2)/4=(2+√2)/2
