与会dd1
幼苗
共回答了21个问题采纳率:90.5% 举报
x^n=(x-1+1)^n
=(x-1)^n+n(x-1)^(n-1)+.+n(x-1)^1+1
则(x^n-1)/(x-1)=(x-1)^(n-1)+n(x-1)^(n-2)+.n(n-1)(x-1)/2+n
则lim(x->1):(x^n-1)/(x-1) =n
2.
x^n-1=(x-1)(x^(n-1)+x^(n-2)+.+1)
lim(x-->1):(x^n-1)/(x-1)=lim(x^(n-1)+x^(n-2)+.+1)=n
1年前
5