Author 
Topic 

clavezza
New Member
USA
2 Posts 
Posted  08/31/2007 : 23:17:01

I am not sure how to solve this particular problem:
2 + 6 + 18 + ... + 2 * 3 to the n1 power = 3n  1
Thanks for the help
Chris 


Ultraglide
Advanced Member
Canada
299 Posts 
Posted  09/01/2007 : 00:42:41

I'm not sure what your problem is, could you clarify it? 


Ultraglide
Advanced Member
Canada
299 Posts 
Posted  09/01/2007 : 00:43:54

Is it a summation? Are you proving by induction? 


Subhotosh Khan
Advanced Member
USA
9116 Posts 
Posted  09/01/2007 : 12:23:35

quote: Originally posted by clavezza
I am not sure how to solve this particular problem:
2 + 6 + 18 + ... + 2 * 3 to the n1 power = 3n  1
Thanks for the help
Chris
Factor out 2  then you have a GP series. 


clavezza
New Member
USA
2 Posts 
Posted  09/01/2007 : 12:35:00

SOrry,
Suppose to use mathematical induction to prove that the statements are true for every positive integer n.
chris 


sahsjing
Advanced Member
USA
2399 Posts 
Posted  09/01/2007 : 19:51:07

n = 1 2 = 3^(1)1 It works. Assume at n = k, 2 + 6 + 18 + ... + 2 * 3 ^(k1) = 3^(k)  1 At n = k+1, 2 + 6 + 18 + ... + 2 * 3 ^k = 2 + 6 + 18 + ... + 2 * 3 ^(k1) + 2*3^k = 3^(k)  1 + 2*3^k = 3^k(1+2)1 = 3^(k+1)  1




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