Re: Combine sqrts in denominator

*To*: mathgroup at smc.vnet.net*Subject*: [mg122417] Re: Combine sqrts in denominator*From*: Szabolcs Horvát <szhorvat at gmail.com>*Date*: Fri, 28 Oct 2011 05:33:21 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*References*: <j8bcf3$8s3$1@smc.vnet.net>

On 2011.10.27. 12:40, Tom D wrote: > I'm doing a calculation that results in terms of the form > > 1/ Sqrt[ -h + Sqrt[h^2 + r^2]] * 1/Sqrt[h + Sqrt[h^2 + r^2]] * (other > functions) > > One sees that this simplifies to (other functions)/r. > > It would helpful to make Mathematica perform this simplification, but > I have not been able to get Simplify[] or FullSimplify[] or anything > else to do it. > > How would I be able to do this? > Tell Mathematica that h and r are positive reals: Simplify[1/(Sqrt[-h + Sqrt[h^2 + r^2]] Sqrt[h + Sqrt[h^2 + r^2]]), h > 0 && r > 0] In Mathematica, saying that they're positive implies that they're real.