Re: rationalize numerator of quotient

*To*: mathgroup at smc.vnet.net*Subject*: [mg81208] Re: rationalize numerator of quotient*From*: Peter Breitfeld <phbrf at t-online.de>*Date*: Sat, 15 Sep 2007 04:18:06 -0400 (EDT)*References*: <29319569.1189724898261.JavaMail.root@eastrmwml14.mgt.cox.net> <fcdf9p$plc$1@smc.vnet.net>

Murray Eisenberg schrieb: > Thanks to all who replied, either here or privately. I didn't try the > "obvious" method of using Simplify because, of course, I forgot > Mathematica's conception of "simpler". > > And this is a good example where Mathematica's "simplify" is contrary to > what is taught in school about when a fraction is simpler -- in high > school it is often (unfortunately) taught that one should "rationalize" > the fraction so that the square-root is in the numerator and never in > the denominator. Of course in calculus, when taking limits of such > quotients, that is precisely what you do NOT want to do, but instead > want to do what Mathematica's sense of simplifying here accomplishes. > [ little bit off-topic ] I think this is relict of the times roots had to be calculated by hand. To calculate 1/Sqrt[2] you first had to calculate Sqrt[2]=1.4142 and then divide 1/1.4142. This is more work to be done than simply dividing Sqrt[2] by 2. Gruss Peter -- ==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-== Peter Breitfeld, Bad Saulgau, Germany -- http://www.pBreitfeld.de

**Follow-Ups**:**Re: Re: rationalize numerator of quotient***From:*Andrzej Kozlowski <akoz@mimuw.edu.pl>