Algebra

Cool goIITian

Joined: 23 Dec 2011
Post: 70
21 Feb 2012 13:24:24 IST
4 People liked this
5
431 View Post
Summation (AGS).
Engineering Entrance , JEE Main , JEE Main & Advanced , Mathematics , Algebra

Sum to infinity: 1 + 1/5 +3/5sq + 5/5cb.......



Comments (5)


New kid on the Block

Joined: 21 Feb 2012
Posts: 1
21 Feb 2012 14:10:34 IST
1 people liked this

find nth termand then apply method of difference..u'll get the result
hemang's Avatar

Blazing goIITian

Joined: 27 Dec 2010
Posts: 1508
21 Feb 2012 14:20:55 IST
3 people liked this

let x = 1 + 1/5 + 3/5^2 + 5/5^3 ....

x/5 = 1/5 + 1/5^2 + 3/5^3 ....

on subtracting we get,

4x/5 = 1 + 2/5^2 + 2/5^3 + ...

4x/5 = 1 + 2(1/5^2 + 1/5^3 + ...

4x/5 = 1 + 2(1/25)/(1-1/5)

4x/5 = 1 + 1/5 = 6/5.

x = 3/2.

there may be some mistake. i am dizzy...

 

Abhishek Bandiya's Avatar

Cool goIITian

Joined: 7 Jul 2011
Posts: 59
22 Feb 2012 15:12:41 IST
0 people liked this

a little bit mistake ,but concept of you two is exactly right,only this matters

Abhishek Bandiya's Avatar

Cool goIITian

Joined: 7 Jul 2011
Posts: 59
22 Feb 2012 15:13:56 IST
0 people liked this

a little bit mistake ,but concept of you two is exactly right,only this matters

hemang's Avatar

Blazing goIITian

Joined: 27 Dec 2010
Posts: 1508
22 Feb 2012 18:08:50 IST
0 people liked this

i found my mistake now.

sorry for it.

4x/5 = 1 + 2(1/25)/(1-1/5)

then 4x/5 = 1 + 1/10 = 11/10.

so, x = 11/8 = 1.375

done.... thanks abhishek. appreciate it.

 




Quick Reply


Reply

Some HTML allowed.
Keep your comments above the belt or risk having them deleted.
Signup for a avatar to have your pictures show up by your comment
If Members see a thread that violates the Posting Rules, bring it to the attention of the Moderator Team
Free Sign Up!
Sponsored Ads

Preparing for JEE?

Kickstart your preparation with new improved study material - Books & Online Test Series for JEE 2014/ 2015


@ INR 5,443/-

For Quick Info

Name

Mobile

E-mail

City

Class

Vertical Limit

Top Contributors
All Time This Month Last Week
1. Bipin Dubey
Altitude - 16545 m
Post - 7958
2. Himanshu
Altitude - 10925 m
Post - 3836
3. Hari Shankar
Altitude - 10085 m
Post - 2217
4. edison
Altitude - 10825 m
Post - 7804
5. Sagar Saxena
Altitude - 8635 m
Post - 8064
6. Yagyadutt Mishr..
Altitude - 6330 m
Post - 1958

Find Posts by Topics

Physics

Topics

Mathematics

Chemistry

Biology

Parents Corner

Board

Fun Zone