原式=x³/(x+1)-(x²-x+1)
=x³/(x+1)-(x+1)(x²-x+1)/(x+1)
=[x³-(x+1)(x²-x+1)]/(x+1)
=[x³-(x³+1)]/(x+1)
=-1/(x+1)
计算：x³/(x+1)-x²+x-1
原式=x³/(x+1)-(x²-x+1)
=x³/(x+1)-(x+1)(x²-x+1)/(x+1)
=[x³-(x+1)(x²-x+1)]/(x+1)
=[x³-(x³+1)]/(x+1)
=-1/(x+1)