Tìm các giới hạn sau: b, lim( căn n^2 +2n +3 - căn 3 của n^2 +n^3)

b)  limn2+2n+3−n2+n33=limn2+2n+3−n+limn−n2+n33.

Mà

 limn2+2n+3−n=limn2+2n+3−n2n2+2n+3+n=lim2+3n1+2n+3n2+1=21+1=1.

 limn−n2+n33=limn3−n2+n3n2+n.n2+n33+n2+n332

 =lim−11+1n+13+1n+132=−11+1+1=−13.

Vậy  limn2+2n+3−n2+n33=1−13=23.