Розвязать уравнение x^-6 +2x^-3=-1

x1 = -1.00000000000000x2 = 0.5 - 0.866025403784439*ix3 = 0.5 + 0.866025403784439*i*sqrt(426)*i)^(1/3)) + (55 + 3*sqrt(426)*i)^(1/3)/3)