sci.math Google Group

Re: Try to solve a quartic equation

jcsan...@fc.up.pt (José Carlos Santos) — Sat, 31 Jul 2010 08:28:34 UT

You don't know. Some times it is and some times it isn't.
Best regards,
Jose Carlos Santos

Re: What happens to the weight of energy in a black hole?

priga...@aol.com (DougC) — Sat, 31 Jul 2010 08:23:55 UT

Gravity bends light. Easily observed. Look up "lensing."
Light does not reflect when it hits a black hole. That's why it
remains black and why it is called a hole.
Doug Chandler

Try to solve a quartic equation

wood0...@sohu.com (Wood) — Sat, 31 Jul 2010 07:53:42 UT

I am trying to learn how to solve a quartic equation. In
"Summary of Ferrari's method" of page
[link]
a root in the most simple case is
x = -B/4/A + sqrt((-alfa + sqrt(alfa^2 - 4*gama))/2)
My question is how to know the express inside sqrt is not negative:
how to know

Re: Quartic equation

wood0...@sohu.com (Wood) — Sat, 31 Jul 2010 07:49:29 UT

Thank you. I think I know now.
I got second question for the quartic equation and will post my new question.

Re: Tricky Answers

ma...@rdrop.remove.com (William Elliot) — Sat, 31 Jul 2010 07:42:15 UT

Does sin^2 x = sin sin x?

Re: Quartic equation

jcsan...@fc.up.pt (José Carlos Santos) — Sat, 31 Jul 2010 07:20:55 UT

Why don't you try to do that and then, if you find an obstacle, you
tell us what that obstacle was?
Besides, when you find a plus/minus sign with subscript _s_, always
choose + or always choose -. If you find a minus/plus sign with
subscript _s_ do the opposite choice. The same thing applies to the _t_

Re: Quartic equation

rgvick...@shaw.ca (Ray Vickson) — Sat, 31 Jul 2010 07:17:04 UT

You get two solutions: one by choosing the '+' sign and another by
choosing the '-' sign. The Wiki article makes this clear.
R.G. Vickson

Re: Solution space of sum atan(x_k)
golabid...@gmail.com (Golabi Doon) — Sat, 31 Jul 2010 07:07:51 UT
In the second example, I meant to write arctan(sum_k x_k^3) < a^2 , so
that there is one application of arctan.
Golabi

Solution space of sum atan(x_k)
golabid...@gmail.com (Golabi Doon) — Sat, 31 Jul 2010 06:59:20 UT
Hello,
Consider the problem:
sum_k arctan(x_k) < a
where k=1,...n and x_k are real variables and "a" is a given constant.
You choose a specific choice of values for x_1,...x_n and give it to
me. I should give you one of these two answers: "your choice satsfies
the inequality" or "I don't know". Of course, I would like to avoid

STATIC UNIVERSE: EINSTEINIANA'S NEW MONEY-SPINNER

pva...@yahoo.com (Pentcho Valev) — Sat, 31 Jul 2010 06:07:04 UT

The old money-spinner:
[link]
"More than a dozen ground-based Dark Energy projects are proposed or
under way, and at least four space-based missions, each of the order
of a billion dollars, are at the design concept stage."
The new money-spinner (in Einsteiniana's schizophrenic world it can

scientists and a glimpse of theory making

plutonium.archime...@gmail.com (Archimedes Plutonium) — Sat, 31 Jul 2010 05:41:31 UT

Supporting evidence comes from observational evidence of those
exoplanets which
Oldershaw is referring to, whereas yours is what? your brain thinking
and hence not
allied with any factual data.
It is the observational factual data that separates the Big Bang as a
fake from the
Atom Totality.
Osher, your posts seem to always lack the allying of factual observed

Re: Attraction of opposite electric charges would form neutronium

macromi...@yahoo.com (BURT) — Sat, 31 Jul 2010 05:37:14 UT

If they never come together by their attraction then it doesn't even
count.
Mitch Raemsch

Re: What happens to the weight of energy in a black hole?

macromi...@yahoo.com (BURT) — Sat, 31 Jul 2010 05:34:56 UT

If light doesn't slow down in empty space it has no escape velocity
like matter. Outgoing light cannot be dragged backward into a black
hole. Gravity can never overcome light.
Mitch Raemsch

Re: Quartic equation

wood0...@sohu.com (Wood) — Sat, 31 Jul 2010 05:20:21 UT

Thanks a lot!
I really want to have a try, but don't know how to deal with the plus-minus-s......is this possible...I mean possible....give me a numerical example following the "Summary of Ferrari's method"?

Re: KISS4691, a potentially top-ranked RNG.

g.bo...@auckland.no.spam.ac.nz (Gib Bogle) — Sat, 31 Jul 2010 05:14:58 UT

orz wrote:
Interesting, who would have guessed that there is a language in which sign(-1) = 0.

sci.math Google Group

Re: Try to solve a quartic equation

Re: What happens to the weight of energy in a black hole?

Try to solve a quartic equation

Re: Quartic equation

Re: Tricky Answers

Re: Quartic equation

Re: Quartic equation

Re: Solution space of sum atan(x_k) golabid...@gmail.com (Golabi Doon) — Sat, 31 Jul 2010 07:07:51 UT In the second example, I meant to write arctan(sum_k x_k^3) < a^2 , so that there is one application of arctan. Golabi

STATIC UNIVERSE: EINSTEINIANA'S NEW MONEY-SPINNER

scientists and a glimpse of theory making

Re: Attraction of opposite electric charges would form neutronium

Re: What happens to the weight of energy in a black hole?

Re: Quartic equation

Re: KISS4691, a potentially top-ranked RNG.

Re: Solution space of sum atan(x_k)
golabid...@gmail.com (Golabi Doon) — Sat, 31 Jul 2010 07:07:51 UT
In the second example, I meant to write arctan(sum_k x_k^3) < a^2 , so
that there is one application of arctan.
Golabi