The Math Forum

Search All of the Math Forum:

Views expressed in these public forums are not endorsed by NCTM or The Math Forum.

Math Forum » Discussions » sci.math.* » sci.math

Notice: We are no longer accepting new posts, but the forums will continue to be readable.

Topic: adding irrational numbers
Replies: 14   Last Post: Oct 10, 2012 3:13 PM

Advanced Search

Back to Topic List Back to Topic List Jump to Tree View Jump to Tree View   Messages: [ Previous | Next ]

Posts: 1,923
Registered: 1/29/05
Re: adding irrational numbers
Posted: Aug 12, 2012 12:30 PM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply

Am Samstag, 11. August 2012 15:33:22 UTC+2 schrieb calvin:
> On Aug 11, 6:07 am, (Richard Tobin) wrote:

> > calvin  <> wrote:
> > >2) Are there any known examples of irrationals not
> > > made up in this way which have rational sums?
> >
> > Just subtract any irrational from any rational - the difference will
> > of course be irrational too.  e.g.  pi + (4-pi) = 4.
> Yes, and thanks to you and quasi, but that's
> not really saying much of anything about adding
> irrationals, when the irrational just cancels
> out. My example was contrived, too, I know.

Maybe this is more along the line you are looking for:
Consider the polynomial f(X) = X^3 -42 X^2 + pi X -sqrt(2)
I have no idea about the exact value of the three (complex) roots
of this guy, but I do know
1) they are transcendental
2) their sum is rational, namely 42
3) their product is algebraic, namely sqrt(2)


Point your RSS reader here for a feed of the latest messages in this topic.

[Privacy Policy] [Terms of Use]

© The Math Forum at NCTM 1994-2018. All Rights Reserved.