lim(x->0)(xcotx-1/x^2)=lim(x->0)(cosx*(x/sinx)-1/x^2) lim(x->0)(x/sinx)=lim(x->0)1/(sinx/x)=1 =-∞y=ln√(1-x)/arccosxy'=[ [-1/2√(1-x)]/√(1-x) ]/arccosx +ln√(1-x)*(-1/√(1-x^2)) ...