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Algebra 2 help

1/1+1/2+1/3+1/4...1/n

 

for what values of n does it make the sum an integer?

how?


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7 helpful answers

Wink

14

Posted 2009-06-14T01:18:00Z
willow4455 was invited by Yedda to answer this question.

 
Ian
67 helpful answers

Let the sum to n terms be called S(n)

S(1) = 1/1 = 1 this is the only integer

S(2) = 3/2 not an integer

S(3) = 1/1+1/2+1/3 = 11/6 not an integer

S(4) = 1/1+1/2+1/3+1/4 = 25/12 not an integer

Similarly S(5) = 137/60, S(6) = 49/20,  S(7) = 363/140

Generally speaking, adding the next fraction makes the result more complicated.

This is not a formal proof of course, but it seems that they are all fractions.

By the way

S(14) = 1171733/360360

So possibly KatieDidIt! was pulling your leg

Hope this will do,

Regards - Ian

Posted 2009-06-14T11:27:36Z
Ian was invited by Yedda to answer this question.

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