wangchusnk
幼苗
共回答了22个问题采纳率:95.5% 举报
lim(n^2+1/n+1+an-b)
=lim(n^2+1/n+1+(an-b)(n+1)/n+1)
=lim[(1+a)n^2+(a-b)n+(1-b)]/ (n+1)
又 lim(n^2+1/n+1+an-b)=1,可知:
[(1+a)n^2+(a-b)n+(1-b)]/ (n+1)中[(1+a)n^2的系数1+a=0,即a=-1
故:lim(n^2+1/n+1+an-b)
=lim[(1+a)n^2+(a-b)n+(1-b)]/ (n+1)
=lim[(a-b)n+(1-b)]/ (n+1)=1
则有:a-b=1,即b=a-1=-2
故:a=-1,b=-2
1年前
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