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sqrt(x/(x-1)) = sqrt(x)/sqrt(x-1)?

Name: Anonymous 2008-03-28 18:06

All right, so it's kind of obvious that they are equal for x >= 0 (the latter may be different because of the domain of sqrt), but is it true that they are always equal?

Using x = -4 as an example:
sqrt(-4/-5) = 2*sqrt(5)/5
sqrt(-4)/sqrt(-5) = (2i)/(sqrt(5)*i) = 2*sqrt(5)/5

Name: Anonymous 2008-03-28 18:15

You are a true nigger.

Name: 4tran 2008-03-28 18:37

x = 1/2

Name: Anonymous 2008-03-28 18:46

Ah, I didn't even think to look on 0 < x < 1, but I suppose I should have. Thanks.

Name: Anonymous 2008-03-29 1:44

In complex field it is valid that sqrt(ab)=sqrt(a)sqrt(b) if and only if -π<arg(a) + arg(b)<=π

Name: CSharp !FFI4Mmahuk 2008-03-29 10:22

That property is always true when both roots are of non-negative numbers. When one or both of them get you complex answers, it's not always true. In fact, misusing that property is one of the more popular ways to "prove" that 2 = 1.

Name: Anonymous 2008-03-29 16:27

sqrt(a/b)=(a/b)^(1/2)=[a*(b^-1)]^1/2=(a^1/2)*(b^-1/2)=sqrt(a)/sqrt(b)
Laws of indicies, learn them

Name: 4tran 2008-03-29 22:48

>[a*(b^-1)]^1/2=(a^1/2)*(b^-1/2)
lol phail

Name: Anonymous 2008-03-30 3:02

Read SICM

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