if An=[2−n43−n3], then ∑∞n=1|An|=
0
1
-1
1/3
|An|=32n−43n ∑∞n=1|An|=3−2=1
If A=⎡⎢⎣111111111⎤⎥⎦, prove that An=⎡⎢⎣3n−13n−13n−13n−13n−13n−13n−13n−13n−1⎤⎥⎦,n∈N.
limn→∞ n((2n+1)2)(n+2)(n2+3n−1) =