3 d + 1 ---------- 2 d - d + 1
(d^3 + 1)/(d^2 - d + 1) при d = 1
(d^3 + 1)/(d^2 - d + 1)
((1)^3 + 1)/((1)^2 - (1) + 1)
(1^3 + 1)/(1^2 - 1 + 1)
2
(1.0 + d^3)/(1.0 + d^2 - d)
3 1 + d -------------- 1 + d*(-1 + d)
1 + d