求极限x趋向于无穷大(x-x^2ln(1+1/x))的做法答案是1/2诶做不出x^2×(ln(1+1/x))

Question

求极限x趋向于无穷大 (x-x^2ln(1+1/x))的做法 答案是1/2
诶 做不出
x^2×(ln(1+1/x))

Answer 1

令x=1/t,则t趋向0原式化成
lim[1/t-ln(1+t)/t^2]=lim[t-ln(1+t)]/t^2
=lim[1-1/(1+t)]/2t (罗必达法则)
=lim1/2(1+t)=1/2