急救!高数极限题,会做的进来帮忙!
1个回答

令t=1/x,则

W=lim(t+2^t)^(1/t) (t->0)

=lim[1+(t+2^t-1)]^{[1/(t+2^t-1)][(t+2^t-1)/t]} (t->0)

=lim e^[(t+2^t-1)/t] (t->0) .利用重要极限lim(1+1/n)^n=e(n->+∞)

=e^lim[(t+2^t-1)/t] (t->0)

=e^lim(1+2^t*ln2) (t->0) .L'Hospital法则

=e^(1+ln2)

=2e