(t^3+1-1)/(t+1) 3次方根最后化简 t^2-t+1-1/(1+t)
(t^3)/(t+1)=(t+1-1)^3/(t+1) =[(t+1)^3-3*(t+1)^2+3*(t+1)-1]/(t+1) =(t+1)^2-3*(t+1)+3-1/(t+1) =t^2-t+1-1/(t+1)