Sum of series.............hav a taste of this...

I remember Nishant Bhaiya's face when he was discussing this problem....well he hates this type of abstract problems but i love this one....

find the value of:\sum_{1}^{\propto }{(1/i)}

well i warn sum of H.P. has no formula.....ise karne ka sirf gadha ghora hi gadha ghora tarika hai...:):P

41 Answers

1
harsh jindal ·

i think u know about my brother!!!!!
he is in delhi iit computer science M.Tech (Ashish Jindal ,AIR 223 IIT JEE 2007)

49
Subhomoy Bakshi ·

nishant bhaiya....how to end the solution??? and harsh's reason look good!! What will be the answer in this case??

62
Lokesh Verma ·

yes that is the way

harsh has done is absolutely correct...

This was the latest sms of the day ?! :)

62
Lokesh Verma ·

see that we have infinitely; many clubbed terms each greater than 1/2..

So the total sum will be greater than infinity :)

66
kaymant ·

That's an interesting statement: "So the total sum will be greater than infinity :)" [1]

62
Lokesh Verma ·

\\1/2+1/3+1/4+1/5+1/6+1/7+1/8+1/9+1/10+1/11+.................... \\1/2+(1/3+1/4)+(1/5+1/6...+1/8)+(1/9+1/10+...1/16)+....... \\>1/2+2\times1/4+4\times1/8+8\times1/16+........ \\>\infty\times 1/2

62
Lokesh Verma ·

arrey sir bhawna ko samajhiye :P ;)

49
Subhomoy Bakshi ·

LOL....yes i liked it too...

So the total sum will be greater than infinity :)

1
harsh jindal ·

what SMS are u talking about?????

62
Lokesh Verma ·

see the proof of the same and you will realize that you are using the same thing as the proof given here in this thread [3]

49
Subhomoy Bakshi ·

yes!!!

1
harsh jindal ·

ha ha he he [4]
it is famous summation
my brother told me its solution in summer holidays of +1[3]

1
harsh jindal ·

pleaze tell me about the SMS !!!! i had made account on targetiit 1.5-2 month ago??

49
Subhomoy Bakshi ·

go to http://www.targetiit.com

and register for the sms services!!

its free too!![1][1]

1
harsh jindal ·

ok , i try to register
thanks [1]

62
Lokesh Verma ·

Cant think of any Gallardo...

Do you knwo of any?

What about \sum{\frac{1}{r^{1.5}}}

62
Lokesh Verma ·

I dont think that helps..

because the lim sup of the limit is 1, that too it approaches from a value of less than 1...

So we cannot give any conclusion...

1
harsh jindal ·

well , there is an another method to prove the same thing
convert the summation in form of integration
\sum_{r=1}^{\propto }{\frac{1}{r}}=\sum_{r=1}^{\propto }{\frac{1/n}{r/n}}
here put
Limit (n→∞)
and convert it to definite integration
\int_{0}^{1}{\frac{1}{x}}dx
it will shows that sum is not finite

39
Pritish Chakraborty ·

Finally the sum made sense harsh! thanks for the summation of series way...lol.

1
archana anand ·

S(n)=1+1/2+1/3+1/4+1/5+...+1/n
S(1)=1
S(2)=(2+1)/2!
S(3)=(3!+3+2!)/3!
S(4)=(4!+4x3+4x2+3!)/4!
S(5)=(5!+5x4x3+5x4x2+5x3x2+4!)/4!
The stuff in parentheses forms the following pattern:
S(5)=(5!+5!/2+5!/3+5!/4+5!/5)/5!
We can divide top and bottom by 5! and get:
S(5)=1+1/2+1/3+1/4+1/5
Oops!

That's what we started with. All I did was show that S(5)=S(5). Actually, we can go directly from the last step (just above the Oops!) to the step above that with all of the 5! in it. Just multiply top and bottom by 5!

It turns out that there is a relatively simple estimate of the sum of n terms:

S(n) is approximately ln(n)+.5772156649...
It gets closer, the larger n is. The number .5772156649... is known as Euler's constant (or the Euler-Mascheroni constant), and is represented by a small gamma.

1
ayush_gupta ·

hey guys whats the ans????

49
Subhomoy Bakshi ·

21
eragon24 _Retired ·

S_{\infty }=\lim_{n\rightarrow \infty }\int_{0}^{1}{\frac{1-x^{n}}{1-x}}dx

will this help.....or not[3]

btw i dun hav any idea abt ur gadha ghora method[3].......surely hearing from u tat term first time....may be its called something else also....

1
Unicorn--- Extinct!! ·

WHAT IS "gadha ghora" method?
Is it hit-n-trial?

49
Subhomoy Bakshi ·

GADHA GHORA method means ass-horse method:P

not that ass tho :P

any ways the process is approximation not hit and trial

62
Lokesh Verma ·

lol..

was my face like that :D

Aise this is not that bad! I think this is a important sum to find! (atleast to konw ;))

29
govind ·

so wat is the answer actually??
i think it shud be nearly 3.5

62
Lokesh Verma ·

okie.. try to prove this

The sum given is not finite! [1]

by comparing or showing that it is larger than another infinite series.

49
Subhomoy Bakshi ·

yea.............or drawing the graph of y=1/x......and finding area...[3][3][3]

49
Subhomoy Bakshi ·

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