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Root sum equals integer (Posted on 2015-03-10) Difficulty: 3 of 5
Find all integers n for which √(25/2 + √(625/4 –n)) + √(25/2 - √(625/4 –n)) is an integer.

No Solution Yet Submitted by K Sengupta    
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re(4): solution & playing around | Comment 6 of 7 |
(In reply to re(3): solution & playing around by Charlie)

Surprising, because:

4k^4+8k^3-44k^2-48k+144 = 4(k-2)^2(k+3)^2
(2*p^2 + 10p)^2 = 4p^2(p+5)^2

Let k=(p+2), then the formulae look very much the same.



  Posted by broll on 2015-03-10 22:49:35
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