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? edited 2×, last 02.10.11 08:58:34 am
Admin/mod comment
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 edited 2×, last 02.10.11 01:05:16 pm
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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