Question

求极限limn→1(1/x-1-3/x³-1)

Answer 1

原式=limx→1 [(x^2+x+1)-3]/(x^3-1)
=limx→1 (x-1)(x+2)/(x-1)(x^2+x+1)
=limx→1 (x+2)/(x^2+x+1)
=(1+2)/(1+1+1)
=1.