问题
填空题
|
答案
[lim n→∞
+1 1•4
+1 4•7
+…+1 7•10
]1 (3n-2)(3n+1)
=lim n→∞
[(1-1 3
)+(1 4
-1 4
)+…+(1 7
-1 3n-2
)1 3n+1
=lim n→∞
(1-1 3
)1 3n+1
=lim n→∞
•1 3
=3n 3n+1
．1 3
故答案为
．1 3
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