Difference between revisions of "1991 AIME Problems/Problem 15"

 
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== Problem ==
 
== Problem ==
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For positive integer <math>n_{}^{}</math>, define <math>S_n^{}</math> to be the minimum value of the sum
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<center><math>\sum_{k=1}^n \sqrt{(2k-1)^2+a_k^2},</math></center>
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where <math>a_1,a_2,\ldots,a_n^{}</math> are positive real numbers whose sum is 17. There is a unique positive integer <math>n^{}_{}</math> for which <math>S_n^{}</math> is also an integer. Find this <math>n^{}_{}</math>.
  
 
== Solution ==
 
== Solution ==
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{{solution}}
  
 
== See also ==
 
== See also ==
* [[1991 AIME Problems]]
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{{AIME box|year=1991|num-b=14|after=Last question}}

Revision as of 02:43, 2 March 2007

Problem

For positive integer $n_{}^{}$, define $S_n^{}$ to be the minimum value of the sum

$\sum_{k=1}^n \sqrt{(2k-1)^2+a_k^2},$

where $a_1,a_2,\ldots,a_n^{}$ are positive real numbers whose sum is 17. There is a unique positive integer $n^{}_{}$ for which $S_n^{}$ is also an integer. Find this $n^{}_{}$.

Solution

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See also

1991 AIME (ProblemsAnswer KeyResources)
Preceded by
Problem 14
Followed by
Last question
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
All AIME Problems and Solutions