⑴.lim(arcsinx/x) [ x→0]=lin(y/siny)[y=arcsinx→0]=1
⑵.打错,应该是[n→+∞]
lim(2^n*sin[x/2^n])(x不等于零的常数) [n→+∞]
=lin{x*sin[x/2^n]/(x/2^n)}=x*lin{sin[x/2^n]/(x/2^n)}=x
⑶lim(tanx-sinx)/sin^3(x) [x→0]=lin{[sinx-sinxcosx]/[cosxsin³x]}
=lin{[1-cosx]/sin²x}=lin{sinx/[2sinxcosx]}=1/2