若lim_x->0 f(x)/x^2=2,则lim_x->0 f(x)/1-cosx=
问题描述：
若lim_x->0 f(x)/x^2=2,则lim_x->0 f(x)/1-cosx=
答
lim_x->0 f(x)/(1-cosx)=lim_x->0 [f(x)/x^2]*[x^2/(1-cosx)]=lim_x->0 [f(x)/x^2]* lim_x->0 [x^2/(1-cosx)]=2*lim_x->0 [x^2/(1-cosx)]=2*2=4(因为1-cosx = x^2/2+o(x^2),所以 lim_x->0 [x^2/(1-cosx)] ＝ lim_x->...