+0  
 
0
2076
1
avatar+69 

Use Sigma Notation to write the following sums.

 

a) 1/4 + 3/8 + 7/16 + 15/32 + 31/64

 

 

b) 1/2+ 2/4 + 6/8 + 24/16 + 120/32 + 720/64

 

 

 

(Note: Any tips or methods in finding the answer are much apreciated) 

 May 22, 2016

Best Answer 

 #1
avatar+118613 
+10

a) 1/4 + 3/8 + 7/16 + 15/32 + 31/64

 

I noticed that the differentces in the numerator were  2, 4, 8, 16    and these are powers of 2. So...

 

\(\displaystyle\sum_{n=1}^{n=5}\;\frac{2^n-1}{2^{n+1}}\)

 

 

b) 1/2+ 2/4 + 6/8 + 24/16 + 120/32 + 720/64

 

 

\(\displaystyle\sum_{n=1}^{n=6}\;\frac{n!}{2^n}\)

 May 23, 2016
 #1
avatar+118613 
+10
Best Answer

a) 1/4 + 3/8 + 7/16 + 15/32 + 31/64

 

I noticed that the differentces in the numerator were  2, 4, 8, 16    and these are powers of 2. So...

 

\(\displaystyle\sum_{n=1}^{n=5}\;\frac{2^n-1}{2^{n+1}}\)

 

 

b) 1/2+ 2/4 + 6/8 + 24/16 + 120/32 + 720/64

 

 

\(\displaystyle\sum_{n=1}^{n=6}\;\frac{n!}{2^n}\)

Melody May 23, 2016

3 Online Users

avatar