Hi, guys!
Basically, my maths problem is the following: I need to check whether sqrt(a+/-sqrt(b)) can be changed into u +/- v, where u is some root of some number and v is also some root.
E.g., sqrt(12 - 2sqrt (35)) = sqrt(7) - sqrt(5)
But, sqrt(5 + sqrt(5)) can't be changed in to u + v. My problem is, why can't it be changed? I am stuck on it and just can't do it. Any help?
Thanks in advance!
P.S.: The prohibition of using the word "problem" in titles is really pointless.
EDIT: Got it... But I still don't get the problem...
EDIT: Just wondering, does anyone care? 2× editiert, zuletzt 02.10.11 08:58:34
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the problem is that most people just choose "problem" as title or add random words "important problem" or crap like that (tells us nothing about the actual thread content = useless!). so it actually makes sense to disallow it. /DC Sunnah, I'm sure a lot of people care. I for one care, but can't see shit in that stuff.
As I said in Skype, it's like fishing in an empty swimming pool. It's half impossible to understand too. This is "true" only when a is a round sqrt of another number or when a^z = Round Number sqrt(7) - sqrt(5)
(sqrt(a) - sqrt(b))^2 = a+b - 2*sqrt(a*b)
so, your thing only holds when
a+b is the first number and a*b is the number under the root..
5 can't be expressed as product of two whole numbers.. it's a prime.
so to your question
sqrt(5 - sqrt(5)) = sqrt(5 - 2*sqrt(1.25))
a+b should be 5, and a*b should be 1.25
a = 1.25 / b --> 1.25 / b + b = 5
this has solutions
b = 0.5*(5 +- 2*sqrt(5))
no whole number solution 2× editiert, zuletzt 02.10.11 13:05:16
I got that already, thanks everyone 
Though my way was a bit different. 
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Maths issue with roots
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