Writing a Geometric Series using Sigma / Summation Notation, Ex 2

[ehsanziaee]

The final answer will be sigma from n=1 to infinity (2^n/13^n)(-1)^n+1

[AhmedKhashabaa]

you should add another - sign outside the brackets too
- (-2/13)^n

[alaasolaiman]

wrong answer everyone has mistakes but you are a great doctor

[ttaher]

 I`m student in ksa in FBSU 
Your lessons  Your style of the callouts lessons  very useful and wonderful
  I benefited from your  lessons of two years
thank you so much
keep going

[nikvenkata]

Woah new video! Right when I am doing this over the summer too! Perfect timing man! Thanks!

[Билимот]

We should multiply the final answer by (-1)^n+1

[Dismitum]

The correct function would either be Σ^∞_1 (-1)^(n+1)*(2/13)^n or Σ^∞_0 (-1)^n*(2/13)^(n+1).

[veritasiumaequitasius]

This guy can do anything. Anything but write a capital Sigma correctly, lol.

[gpbiester]

Yes, Patrick is awesome, but he made an error on this problem. You need a power of n+1 to produce an alternating series that starts with a positive number.

[lightningirl]

@patrickJMT wouldn't (-2)^1/13^1 give you -2/13 instead of 2/13? Doen't it give you the wrong sign?

[Voxstep]

what about the + - alternation? how is that expressed in the sigma

[lightningirl]

Doesn't the equation that you gave produce the wrong sign on all of the terms? The first term is positive not negative.

[BruceBmk]

the answer supposed to be sigma from n=1 to infinity -2^n/(-13)^n

[exophyla]

Yeah, the given sum produces a series with the wrong sign :(