A community for students.
Here's the question you clicked on:
 0 viewing
anonymous
 3 years ago
how do you find the sum from n=1 to infinity of n(1/4)^(n1)
anonymous
 3 years ago
how do you find the sum from n=1 to infinity of n(1/4)^(n1)

This Question is Closed

perl
 3 years ago
Best ResponseYou've already chosen the best response.1did you try using the ratio test

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0I thought the ratio test tells you if it is convergent or divergent not what the actual sum is. By the ratio test it is convergent.

perl
 3 years ago
Best ResponseYou've already chosen the best response.1the expression inside looks close to the derivative of 1/4 ^n1

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0how did you get that?

perl
 3 years ago
Best ResponseYou've already chosen the best response.1lets look at the partial sums

perl
 3 years ago
Best ResponseYou've already chosen the best response.1take the sum from n=1 to m

perl
 3 years ago
Best ResponseYou've already chosen the best response.1do you have a justification

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0dw:1353747498242:dw

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0dw:1353747595344:dw

perl
 3 years ago
Best ResponseYou've already chosen the best response.1i could start the second limit at n = 2

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0how did you get 1/(1x)^2 from the step above?

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0dw:1353747789535:dw

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0take the derivative both sides

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0you can also take integral sometimes..

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0I did not notice your series start from 1, answer will be (16/9)1

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0dw:1353748518528:dw

perl
 3 years ago
Best ResponseYou've already chosen the best response.1the answer is correct , it is 16/9

perl
 3 years ago
Best ResponseYou've already chosen the best response.1the first term is zero, so we can ignore it

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0the original solution was correct. the left hand side is defined at n=1, the RHS doesn't have to be defined at 1 because its the formula for the sum of geometric series i.e. r=x.
Ask your own question
Sign UpFind more explanations on OpenStudy
Your question is ready. Sign up for free to start getting answers.
spraguer
(Moderator)
5
→ View Detailed Profile
is replying to Can someone tell me what button the professor is hitting...
23
 Teamwork 19 Teammate
 Problem Solving 19 Hero
 Engagement 19 Mad Hatter
 You have blocked this person.
 ✔ You're a fan Checking fan status...
Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.