[Date Index]
[Thread Index]
[Author Index]
Re: rationalize numerator of quotient
*To*: mathgroup at smc.vnet.net
*Subject*: [mg81174] Re: [mg81125] rationalize numerator of quotient
*From*: Murray Eisenberg <murray at math.umass.edu>
*Date*: Fri, 14 Sep 2007 03:45:19 -0400 (EDT)
*Organization*: Mathematics & Statistics, Univ. of Mass./Amherst
*References*: <29319569.1189724898261.JavaMail.root@eastrmwml14.mgt.cox.net>
*Reply-to*: murray at math.umass.edu
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.
Bob Hanlon wrote:
> y = (Sqrt[x] - 2)/(x - 4);
>
> y // Simplify
>
> 1/(Sqrt[x] + 2)
>
> y // Cancel
>
> 1/(Sqrt[x] + 2)
>
> y // Apart
>
> 1/(Sqrt[x] + 2)
>
>
> Bob Hanlon
>
> ---- Murray Eisenberg <murray at math.umass.edu> wrote:
>> I have a quotient such as:
>>
>> (Sqrt[x] - 2)/(x-4)
>>
>> I want to "rationalize the numerator" by multiplying numerator and
>> denominator each by Sqrt[x] + 2 so as to obtain result:
>>
>> 1/(Sqrt[x]+2)
>>
>> How?
>>
>> --
>> Murray Eisenberg murray at math.umass.edu
>> Mathematics & Statistics Dept.
>> Lederle Graduate Research Tower phone 413 549-1020 (H)
>> University of Massachusetts 413 545-2859 (W)
>> 710 North Pleasant Street fax 413 545-1801
>> Amherst, MA 01003-9305
>>
>
--
Murray Eisenberg murray at math.umass.edu
Mathematics & Statistics Dept.
Lederle Graduate Research Tower phone 413 549-1020 (H)
University of Massachusetts 413 545-2859 (W)
710 North Pleasant Street fax 413 545-1801
Amherst, MA 01003-9305
Prev by Date:
**Re: help plot log[f[t]] vs a parameter using an ODE**
Next by Date:
**Re: Distinguishing Strings from Symbols**
Previous by thread:
**Re: rationalize numerator of quotient**
Next by thread:
**Re: rationalize numerator of quotient**
| |