Question Number 213511 by universe last updated on 07/Nov/24
![lim_(n→∞) [Σ_(r=1) ^n (1/2^r )] where [•] greatest integer finction](https://www.tinkutara.com/question/Q213511.png)
Answered by issac last updated on 07/Nov/24

Commented by mr W last updated on 07/Nov/24

Answered by lepuissantcedricjunior last updated on 09/Nov/24
![lim_(n→+∞) [Σ_(r=1) ^n (1/2^r )]=lim_(n→+∞) [−1+Σ_(r=0) ^n (1/2^r )] =lim_(n→+∞) [−1+((1−((1/2^(n+1) )))/(1−(1/2)))] =lim_(n→+∞) [−1+2(1−2^(−(n+1)) )] =[−1+2]=1](https://www.tinkutara.com/question/Q213569.png)
Commented by mr W last updated on 09/Nov/24

Answered by mr W last updated on 07/Nov/24
![Σ_(r=1) ^n (1/2^r )=(((1/2)(1−(1/2^n )))/(1−(1/2)))=1−(1/2^n )<1, but >0 ⇒[Σ_(r=1) ^n (1/2^r )]=0 ⇒lim_(n→∞) [Σ_(r=1) ^n (1/2^r )]=lim_(n→∞) 0=0 ✓](https://www.tinkutara.com/question/Q213515.png)
Commented by issac last updated on 07/Nov/24

Commented by universe last updated on 07/Nov/24

Answered by Berbere last updated on 07/Nov/24
![[x]<x ⇒0≤[Σ_(r=1) ^n (1/2^r )]≤Σ_(r=1) ^n (1/2^r )=1−((1/2))^n <1 ⇒∀n∈N [Σ(1/2^r )]=0](https://www.tinkutara.com/question/Q213532.png)
Commented by universe last updated on 07/Nov/24
