Re: Can I have fries and a calculator with that?


Dave L. Renfro wrote:
> Dave L. Renfro wrote:
>
> >> I came across the following while searching for
> >> something else. It speaks for itself.
> >>
> >> ----------------------------
> >>
> >> http://www.vbforums.com/showthread.php?referrerid=43870&t=298609
> >>
> >> How do i rationalize the denominator in this?
> >> 6/sqr(x) + sqr(3) I know for somthing like
> >> 7/sqr(4) i can use a rationalizing factor of
> >> sqr(4) to end up getting 7sqr(4)/4 but then
> >> im not sure if this ends up being reduced to
> >> 7sqr(1). So i guess im asking two quesitons.
> >> Thanks.
> >>
> >> ----------------------------
> >>
> >> I'm almost tempted to think this was a troll post
> >> given the "two quesitons" at the end, but I think
> >> doing so requires too much textual interpretation
> >> to be realistic.
>
> Virgil wrote:
>
> > If that denominator is (sqrt(x) + sqrt(3)), you can
> > rationalize it by multiplying the numerator and denominator
> > by (sqrt(x) - sqrt(3)) or by (-sqrt(x) + sqrt(3)).
> >
> > To rationalize a denomonator of sqrt(4), note that
> > sqrt(4) = 2, which is already rational.
>
> Uh ... I think we all know this, or at least I hope we do.
> My point (see thread title) was that this person appears
> to suffer from that malady some people get from calculator
> overuse, where they aren't able to recognize sqrt(4) and
> sqrt(1) as 2 and 1, and where they think sqrt(4) cancels
> 4 in sqrt(4)/4 to produce sqrt(1).
>
> As for rationalizing denominators, here's a less trivial
> example for you. We can rationalize the denominator of 1/b,
> where
>
> b = sqrt(2) + sqrt(10) + sqrt(12) + sqrt(56),
>
> by multiplying the numerator and denominator by f(b), where
>
> f(x) = x^15 - (640)*x^13 + (155,072)*x^11 - (18,296,832)*x^9
>
> + (1,125,983,744)*x^7 - (35,305,193,472)*x^5
>
> + (491,646,992,384)*x^3 - (1,840,594,812,928)*x.
>
> After multiplying, but before reducing, the denominator will be
>
> - 525,242,269,696.
>

I'll take your word for it, lol

.

Relevant Pages

  • Re: Can I have fries and a calculator with that?
    ... Dave L. Renfro wrote: ... > rationalize it by multiplying the numerator and denominator ...
    (sci.math)
  • Re: derivative
    ... but I looked at the .gif again ... just now and the denominator is definitely x. ... Dave L. Renfro ...
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  • Re: derivative
    ... but I looked at the .gif again ... just now and the denominator is definitely x. ... Dave L. Renfro ...
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  • Re: Can I have fries and a calculator with that?
    ... We can rationalize the denominator of 1/b, ... >> After multiplying, but before reducing, the denominator will be ... > w in a similar manner to rationalize w in a denominator. ... where sinseems unobtainable within algebraics. ...
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  • Re: complex division
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