We have,
limn→∞nn2+1+nn2+2+nn2+3+−−−−−+nn2+n
=limn→∞nn2+n
=limn→∞nn⎡⎢ ⎢ ⎢⎣1n+1n⎤⎥ ⎥ ⎥⎦
=limn→∞⎡⎢ ⎢ ⎢⎣1n+1n⎤⎥ ⎥ ⎥⎦
=limn→∞⎡⎢ ⎢ ⎢⎣1∞+1∞⎤⎥ ⎥ ⎥⎦
=1∞
=0
Hence, this is the answer.