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#1 Re: Help Me ! » Cycle length of 1/p » 2009-09-09 03:20:17

Hi bobbym thanks for replying smile . I guess the link that you gave above have cleared all my doubts and concepts I interested in. I appreciate your effort up .

#2 Help Me ! » Cycle length of 1/p » 2009-09-07 17:44:00

coffeeking
Replies: 3

Hi, I am currently taking a course on number theory and was doing some revision on my own. There is one part of the topic that my lecturer has only briefly touches on but has however, sparked my interests.

It's mentioned that for some recurring decimal like 1/23, 1/17 has the property that it will follow the same cycle for any integer multiple of it eg:


and



eek

however recurring decimal like 1/13, 1/37 does not exhibit this trait. May I know what the reasoning behind this is? I really keen to know.

Thanks for your time and I will appreciate if anyone could explain this to me or at least point out on where I should research on to find out the answer.

#3 Re: Help Me ! » Financial Mathematics » 2009-08-10 16:01:46

The series that you are refering to is:

which can be simplified to:

using the formula for geometric series.

I am just doing some practices questions from my textbook on my own by the way.

#4 Re: Help Me ! » Financial Mathematics » 2009-08-09 16:43:50

Hi bobbym thanks for the link. However after following through the working I end up having to solve a 15 degree polynomial:

Are there any easier method?

#5 Help Me ! » Financial Mathematics » 2009-08-09 02:21:23

coffeeking
Replies: 9

Well I have problem understanding this question as I don't even know where to start. Would appreciate if anyone could sheath some light on how to tackle this question or at least give some hint on where to start. dizzy

The Z Corporation issues a 10%, 20-year bond at a time when yields are 10%. The bond has a call provision that allows the corporation to force a bond holder to redeem his or her bond at face value plus 5%. After 5 years the corporation finds that exercise of this call provision is advantageous. What can you deduce about the yield at that time? (Assume one coupon payment per year.)

#6 Re: Help Me ! » More Questions... » 2009-05-20 03:21:57

Thanks. So as to clear thing up if we are given

are we also right to say that
? and also,
implies
?

#7 Re: Help Me ! » More Questions... » 2009-05-19 15:08:49

Hi Avon, thanks for the help I appreciate it up. Anyway, as for the last part of my question I do understand that

implies that
, which is enough to show that the poles of g do not lie in the open unit disk. However, to my understanding
will never implies
because
is exactly equal to 1 and never larger.

Please advise.

#8 Help Me ! » More Questions... » 2009-05-19 02:47:20

coffeeking
Replies: 4

Q1:
Evalute

Where C(0,6) is the positive oriented circle |z|=6 and

I understand that for this question we need to use the Argument Principle in which

However, the solution are given something like:

Zeros in

are:
(order 3)
(order 1)

Therefore

My question is, why as for the sin(z) term we only take 0, pi and -pi? If we are considering only the principal value of argument i.e (-pi,pi] we should only take 0 and pi and not -pi since it does not lies in the interval. Anyone has any idea?


Q2:

Does there exist an entire function f such that

for all positive integers n? Justify your answer.

Alright as for this, the solution is given as:

Consider

then


for all positive integers n.

Now

iff

Therefore if z is a zero of

,
and

Hence g(z) has no poles in D(0,1) and so g is analytic on D(0,1).

Now

for all positive integers n and
in D(0,1) with
.

It follows that for any analytic function f with the given property,

.

However, limit of g at z=-1 does not exist implies that the limit of f at -1 does not exists and so f cannot be analytic at -1 and so f cannot be an entire function. Hence such entire function does not exist.


Well, the thing that I don't understand about this question is that since the function f is defined on positive integers n the domain and image set of f should all be positive so how could we possibly find limit of f at -1 at the very first place?

Furthermore, I don't understand why

implies that
.

Thanks a dozen in advance.

#9 Re: Help Me ! » Questions » 2009-05-18 04:12:06

I think I get the idea. Thanks big_smile

#11 Help Me ! » Questions » 2009-05-17 03:31:34

coffeeking
Replies: 4

Well, there is a corollary on Maximum Modulus Principle that goes like this:

"If

is analytic on a path connected open set
and
attains its maximum value at a point
in
, then
is constant on
."

Well my question are:

1.)Does this statement holds true if I replace "maximum" with "minimum"?

2.)More generally, does Maximum Modulus Principle and all its corollaries the same as Minimum Modulus Principle just that we only have to replace the word "maximum" with "minimum"?

-----------------------------------------------------------------------------------------------------------------
3.) Alright this question is not on Maximum Modulus Principle, it's something regarding the phrasing of Mathematics that I am confused in.

Let's say if we say something like

lies in
is it the same as saying
lies on
?

and the same goes for if

lies in
is it the same as saying
lies on
?


I am asking this because I always though if we say something lie in something such as 

we mean that it is contain inside the circle. Whereas when we say something lies on
, we actually mean that it "sit" right on the circumference of the circle or sometime refer to as
.

However, it seem to me that some textbook just use them interchangeable, could any kind soul confirm this for me?

Thanks and will appreciate if anyone could answer my questions as my exam on Complex Analysis is on next week eek

#12 Re: Help Me ! » Degree of freedom for a Chi-squared test? » 2009-05-12 02:23:02

That it! You are the MAN! touched How could I have forgotten about this? Thanks a bunch.:D

#13 Help Me ! » Degree of freedom for a Chi-squared test? » 2009-05-11 23:59:12

coffeeking
Replies: 3

Hi, may I know the degree of freedom for a chi-squared test? What is given on my notes is k-p-1 where k denote the no. of classes, p denote estimated parameter. However this is one question that really confused me:

30 passengers on a flight took part in an experiment to investigate if a new drug suppresses jet lag. The subjects were divided into two group, one given the course of treatment and the other was given a placebo.


                                   Jet lag                 No jet lag
Treatment group             3                           12
Placebo group                 10                         5


With data above, use a chi-squared test to investigate if the treatment suppressed jet lag.


Solution is given as:

There is no association between experiencing jet lag and the treatment
Treatment suppressed jet lag

The expected frequencies are as follows:

                                  Jet lag                 No jet lag
Treatment group             6.5                        8.5
Placebo group                 6.5                        8.5


Hence the test statistic is:

Degree of freedom:


.
.
.
.

My question is, why is the degree of freedom (2-1)(2-1)=1 ? Isn't it 4-1=3? since no. of classes is 4 and there are no estimated parameter?

Thanks a bunch in advance, I have an exam this week. dizzy

#15 Re: Help Me ! » Harmonic Function » 2009-05-11 03:25:12

could anyone confirm this for me? Thanks.

In addition what about u-v, uv, u/v? Is Laplace equation always the method to check for harmonic?

Thanks in advance.

#16 Re: Help Me ! » Question on improper integrals » 2009-05-11 03:13:54

Hi, thanks for the input bobbym and whatismath, I appreciated it. up

#17 Re: Help Me ! » Question on improper integrals » 2009-05-01 00:51:20

Hi luca, thanks for replying. Anyway since it cannot be solved analytically are there other method of proofing that it is divergent?

#18 Help Me ! » Question on improper integrals » 2009-04-30 20:28:49

coffeeking
Replies: 6

Proof that

is divergent.

I know that in order to prove such a statement you'll first need to find

and show that the limit below does not exist:

However, I have difficulty integrating

at the first place sad

#19 Re: Help Me ! » Geometry: The missing angles of a quadrilateral » 2009-04-30 17:33:27

Construct your quadrilateral with the corners marked from the top right hand side as K, all the way anti-clockwise to N. It will be much easier this way.

#20 Help Me ! » Harmonic Function » 2009-04-30 17:21:06

coffeeking
Replies: 4

Hi, as my exam is round the corner, I just wish to check if my concept is right. Say if

is analytic on a domain D, am I right to say that
is harmonic on domain D?

Since if

is analytic on domain D it will means that
and
are both harmonic on D and hence satisfy Laplace's equation:


Let

then

which also satisfy the Laplace's equation.

So

is harmonic on domain D?

#22 Re: Help Me ! » Algebra - roots of the equation » 2009-04-26 06:53:13

Oh my gosh! Think I am drunk lol big_smile
Hi Jane, thanks for correcting me. Please ignore my previous post. It's late in the night, I'll work this question again tomorrow.

#23 Re: Help Me ! » Algebra - roots of the equation » 2009-04-26 05:48:32

Well I suspect the last line should read:

I not sure if there are simpler method but this is what I have:

Since

are the roots of
and
are the roots of
we'll have:


By expanding and comparing coefficient of both equation we'll get:





Together, we'll get:



Since

, we'll only need to prove that

By expanding and substituting

We'll get

Which completes the proof.

#24 Re: Help Me ! » complex function » 2009-04-26 03:01:16

Hi Ricky thanks for the info up

I have to say that there are lots of helpful helper here thanks! big_smile

#25 Re: Help Me ! » complex function » 2009-04-26 01:57:25

Hi dannyv, thanks for the effort smile

By the way could you elaborate what do you mean by if I write the complex logarithm it is easier?

Thanks.

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