Не доходит
А сделать вот что надо:
-1/(x - 1)^3 + 3/(x -3)^3 = 0
(-(x - 3)^3 + 3 * (x - 1)^3)/((x - 1)^3 * (x - 3)^3) = 0
3 * (x - 1)^3 - (x - 3)^3 = 0
(3^(1/3) * (x - 1)^3 = (x - 3)^3
3^(1/3) * (x - 1) = x - 3
3^(1/3) * x - 3^(1/3) = x - 3
x * (1 - 3^(1/3)) = 3 - 3^(1/3)
x = (3 - 3^(1/3))/(1 - 3^(1/3))
x = 3^(1/3) * (3^(2/3) - 1)/(1 - 3^(1/3))
x = -3^(1/3) * (3^(1/3) - 1) * (3^(1/3) + 1)/(3^(1/3) - 1)
x = -3^(1/3) * (3^(1/3) + 1)
x = -3^(2/3) - 3^(1/3)