[微積] 收斂數列

[tokyo291 (工口工口)]

{a_n} and {b_n} are positive series.

(1) if Σa_n and Σb_n both converge,

    then Σa_n*b_n converges?

(2) if Σa_n and Σb_n both diverge,

    then Σa_n*b_n diverges?

想請問該用哪種審斂法來判斷證明呢?

如果a_n b_n沒有正數的限制(1)為錯 (2)為錯 這樣子是對的嗎?

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