Re: Q: Solve gives complex solution where there is a noncomplex solution how to get the last one?

*To*: mathgroup at smc.vnet.net*Subject*: [mg50321] Re: [mg50300] Q: Solve gives complex solution where there is a noncomplex solution how to get the last one?*From*: Andrzej Kozlowski <akoz at mimuw.edu.pl>*Date*: Fri, 27 Aug 2004 02:57:34 -0400 (EDT)*References*: <200408261050.GAA16310@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

On 26 Aug 2004, at 19:50, Dick Barends wrote: > *This message was transferred with a trial version of CommuniGate(tm) > Pro* > Hello, > > The following line > > Solve[x y / ( 1 + y^2 )^0.5 == a, y] > > Gives a complex solution : (0.+ i )a / (a^2 - x^2)^0.5 > Which is correct but could be simpler, not complex > > The solution I expected is: a/(x^2 - a^2)^0.5 > > How can I instruct Mathematica (Solve) to give the simple solution > directly. > > kind regards > Dick Barends > > > Use Solve[x y / ( 1 + y^2 )^(1/2) == a, y] In Mathematica 0.5 and 1/2 are quite different entities and you should not use them interchangeably. If you really mean the square root you should always use the power 1/2. Andrzej Kozlowski

**References**:**Q: Solve gives complex solution where there is a noncomplex solution how to get the last one?***From:*"Dick Barends" <dick.barends@wxs.nl>