求极限lim(x趋于1）(x^3-ax^2-x+4)/(x+1)=b

题目

求极限lim(x趋于1）(x^3-ax^2-x+4)/(x+1)=b
a b为实数

答案

应该是趋于-1吧?如果是的话,分母上x^3-ax^2-x+4应该含（x+1)因式x^3+x^2-(a+1)x^2-(a+1)x+(a+2)x+(a+2)+4-(a+2)=(x+1)(x^2-(a+1)x+(a+2))+2-a极限lim(x趋于-1）(x^3-ax^2-x+4)/(x+1)=lim(x趋于-1）((x+1)(x^2-(a+1)x...