Question

求极限lim(x→0)[tan3x/x]

Answer 1

lim(x→0)[tan3x/x]=3 lim(3x→0)[tan3x/3x]=3 lim(x→0)[sin3x/3x]lim(x→0)[1/cos3x]=3

lim(x→1)(x^2-2x+1)/(x^2-1)=lim(x→1)(x-1)^2/(x+1)(x-1)=lim(x→1)(x-1)/(x+1)=0