Math Is Fun Forum

  Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °

You are not logged in.

#301 Re: Jokes » "Have I Got News For You" » 2009-09-27 05:13:03

I agree with what you say in post #2. Well, nobody’s perfect. I suppose an American comedy show could similarly make a humorous sketch on the rudeness of, say, British tourists in America, and then everybody can have a good laugh too. smile

#302 Re: Jokes » "Have I Got News For You" » 2009-09-27 04:33:22

bobbym wrote:

If someone uses a disclaimer can they now act like a jerk?

Perhaps, but I don’t see how the video is being a jerk. You should watch HIGNFY – there are loads more scenes like the one in the video, all intended to be funny rather than offensive. Besides, it’s been running for almost 20 years now – surely something that long-runnning can’t possibly be “jerk”.

#303 Re: Jokes » "Have I Got News For You" » 2009-09-27 04:15:59

Yes, but would you agree that the clip itself is hilarious? lol

In any case

DISCLAIMER wrote:

This clip is meant as humour. No offence to any person or group is intended.

“Have I Got News For You” is meant to be a funny comedy show. Lighten up, dude!

#308 Re: Help Me ! » Modulus inequalities » 2009-09-24 23:41:47

Never mind, forget what I said. Sorry.

#309 Re: Help Me ! » infinite series » 2009-09-24 09:20:37

This is one of those arithmetic–geometric hybrid series.

#310 Re: Help Me ! » Modulus inequalities » 2009-09-24 08:42:01


I think mmoadi made a slight typo in (4): I think it should be

#311 Re: Formulas » Science laws and theorems » 2009-09-24 03:49:39

Planck’s radiation law


The intensity per unit wavelength
of the radiation of a black body of absolute temperature
is given by

[align=center]

[/align]
where
is Planck’s constant,
is the speed of light in a vacuum, and
is Boltzmann’s constant.

From this, both Stefan’s law (which states that the intensity of the radiation of a black body is proportional to the 4[sup]th[/sup] power of its absolute temperature) and Wien’s displacement law (which states that the maximum wavelength of the radiation of a black body is inversely proportional to its absolute temperature) can be derived.

To derive Stefan’s law, hold

constant and evaluate
. For Wien’s displacement law, set
.


http://z8.invisionfree.com/DYK/index.php?showtopic=867

#312 Re: Puzzles and Games » Too tough for a homework assignment? » 2009-09-22 08:58:28

I think this question is suitable for final-year GCSE or first-year A-level students.

#313 Re: Puzzles and Games » Too tough for a homework assignment? » 2009-09-21 21:18:17


It’s not difficult. You just need to apply the formula
three times.

#315 Re: Help Me ! » help me plz~ property of S4 » 2009-09-19 04:06:45


Subgroups of
have orders 1, 2, 3, 4, 6, 8, 12, or 24. Obviously there is only one subgroup (up to isomorphism) of each of the orders 1, 2 and 3. There is only one subgroup of
of order 24, namely
, and one subgroup of
of order 12, namely
.

Which leaves 4, 6 and 8. As

does not have any cyclic subgroup of order 6 (if it did it would have to have either a 6-cycle or a disjoint product of a 2-cycle and a 3-cycle, neither of which is possible) all subgroups of order 6 are thus isomorphic (to
). As for 8, notice that
. Hence every subgroup of order 8 is a Sylow 2-subgroup; therefore all subgroups of order 8 are conjugate and therefore isomorphic (to the dihedral group
).

has two nonisomorphic subgroups of order 4, namely
(cyclic) and
(the Klein Viergruppe).

#318 Re: Exercises » Some nasty inequalities » 2009-09-16 05:41:32

I always thought using calculus to tackle these kinds of inequalities is a bit of a brute-force tactic. Much like using the Jordan–Hölder theorem in group theory to prove the fundamental theorem of arithmetic, if you know what I mean. wink

But of course, if calculus works, then there is no reason not to use it, if you know how. Nice work! up

#319 Re: Maths Is Fun - Suggestions and Comments » More About Functions » 2009-09-15 19:05:59

I think what you meant was that a constant function is neither strictly increasing nor strictly decreasing. wink

Well, aren’t constant functions just fascinating? They are both increasing and decreasing, yet neither strictly increasing nor strictly decreasing. Amazing how we take so many things for granted, only to find, on closer inspection, that we have been mistaken all along. smile

#320 Re: Exercises » Some nasty inequalities » 2009-09-15 18:12:08

Well, I can at least start by proving that
.

Quite easy, as it turns out.

In fact, as you can see, the inequality is strict.

So far so good. tongue

#321 Re: Exercises » Some nasty inequalities » 2009-09-15 13:47:25

Wow, they sure look nasty! (At first sight, at any rate.) faint

#322 Re: Maths Is Fun - Suggestions and Comments » More About Functions » 2009-09-15 13:41:31

According to the definition, a function y=f(x) is increasing iff

when x1 < x2 then f(x1) ≤ f(x2)

Hence, if y=f(x) is non-increasing, then there exist x1 < x2 such that f(x1) > f(x2). But a constant function cannot possibly have f(x1) > f(x2). Therefore a constant function cannot be non-increasing.

By a similar argument a constant function cannot be non-decreasing either. Therefore it must be both increasing and decreasing.

#323 Re: Maths Is Fun - Suggestions and Comments » More About Functions » 2009-09-15 13:28:57

About constant functions …

A Constant Function neither increases nor decreases:

You realize that this is wrong? In fact, a Constant Function is both increasing and decreasing (but not strictly) along its whole domain.

Think about it.

#324 Re: Puzzles and Games » Tough Inequality » 2009-09-14 21:35:48

A problem similar to mine can be found here.

#325 Re: Exercises » Integral and inequality » 2009-09-14 13:07:40

mathsyperson wrote:

Are we allowed to express the LHS of the inequality as a Taylor series? If so, the problem becomes trivial.

bobbym wrote:

Thats how I would do it.

The inequality holds for

as well, in which case the method will not be trivial for
.

And note that there is an apostrophe in That’s.

Board footer

Powered by FluxBB