Let
S 0 = 2 8 1 + 4 8 1 + 6 8 1 + …
S 1 = 1 8 1 + 3 8 1 + 5 8 1 + …
If S 1 S 0 = b a where a and b are coprime positive integers , what is the value of a + b ?
This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try
refreshing the page, (b) enabling javascript if it is disabled on your browser and,
finally, (c)
loading the
non-javascript version of this page
. We're sorry about the hassle.
i think i have stole your solution from your brain megh choksi because i've done in this same method... :P
Exactly :) You should check out Steven's Books, they're full of awesome knowledge.
Log in to reply
Isn't it great to be inspired by others? I love posting such questions :)
Downloaded all
Where can you get his books?
Same solution
problem is overrated
So you got the inspiration from my books. No wonder why I don't remember posting a problem like this on Brilliant.
I actually used the method from my findings ζ ( n ) = 2 n − 1 2 n k = 1 ∑ ∞ ( 2 k − 1 ) n 1 .
Yeah, it's full of great findings. Thanks for sharing :)
S 0 = 2 8 1 + 4 8 1 + 6 8 1 + …
S 1 = 1 8 1 + 3 8 1 + 5 8 1 + …
2 8 S 0 = 1 8 1 + 2 8 1 + 3 8 1 + …
2 8 S 0 − S 0 = 1 8 1 + 3 8 1 + 5 8 1 + …
2 8 S 0 − S 0 = S 1
( 2 8 − 1 ) S 0 = S 1
S 1 S 0 = 2 8 − 1 1
a = 1 , b = 2 8 − 1 , a + b = 2 8 = 2 5 6
nice and easy to understand
S 0 = 2 8 1 [ 1 8 1 + 2 8 1 + 3 8 1 +...] = 2 8 n , where n = i = 1 ∑ ∞ i 8 1 . Now it is clear to see that n = S 0 + S 1 , so S 0 = 2 8 S 0 + S 1 . Rearranging gives: 255 S 0 = S 1 , so S 1 S 0 = 2 5 5 1 . ∴ a + b = 256
So+S1 can be expressed as, Sum(n=1...infinity) (1/n^8), while So=Sum(n=1...infinity) [1/(2n)^8]=(1/2^8) Sum(n=1...infinity) (1/n^8). Therefore, (So+S1)/So=2^8=256, So+S1=256So, S1=255So. Therefore, So/S1=1/255, from which a=1 & b=255 so that a+b=256
Problem Loading...
Note Loading...
Set Loading...
S 0 = 2 8 1 ( 1 8 1 + 2 8 1 + 3 8 1 + . . . . . . . . . )
S 1 = 1 8 1 + 3 8 1 + 5 8 1 . . . .
S 0 = 2 8 1 ( S 0 + S 1 )
S 1 S 0 = 2 8 1 ( S 1 S 0 + 1 )
b a = 2 8 − 1 1
a + b = 2 8