计算X2+X+1+X3/1-X=
问题描述：
计算X2+X+1+X3/1-X=
答
(X²+X+1+X³)/(1-X)
=(X³+X²+X+1)/(1-X)
=[X²(X+1)+(X+1)]/(1-X)
=(X²+1)(X+1)/(1-X)