Question

已知lim f(x-1)/(x-1)当x→0时为1 则lim (x-1)/f(2-2x)当x→0时的值为( ) A.-1

Answer 1

令x-1=t则x=t+1

lim f(x-1)/(x-1)=lim f(t)/t=1

(x-1)/f(2-2x)=t/f(-2t)=1/ (-2)*[f(t)/t]

lim (x-1)/f(2-2x)=lim1/ (-2)*[f(t)/t]=-1/2