SOLUTION: Please Help Find the following sum: 1+2+4+8+...+2^k-1 I tried to set it out the following way 1+2+4+8...+2^k-1,?,?,? 2^k-1+?+?+?...+8+4+2+1

Algebra ->  Sequences-and-series -> SOLUTION: Please Help Find the following sum: 1+2+4+8+...+2^k-1 I tried to set it out the following way 1+2+4+8...+2^k-1,?,?,? 2^k-1+?+?+?...+8+4+2+1      Log On


   

Question 973104: Please Help
Find the following sum: 1+2+4+8+...+2^k-1
I tried to set it out the following way
1+2+4+8...+2^k-1,?,?,?
2^k-1+?+?+?...+8+4+2+1
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
Find the following sum: 1+2+4+8+...+2^k-1
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Sum of a geometric series::
S(n) = a[r^n - 1]/[r-1]
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Your Problem::
a = 1, r = 2
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S(k) = [2^k -1]/1 = 2^k - 1
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Cheers,
Stan H.
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