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#1526 Re: Help Me ! » Canonical Cycle Notation » 2014-12-31 02:46:49

Unfortunately, some people do composition on the left, and some do it on the right. In your example, you're doing composition from the left -- i.e. (1 2) is done first, then (1 3):

Applying (1 2):

1 -> 2
2 -> 1
(3 -> 3)

Then applying (1 3):

1 -> 2 -> 2 i.e. 1 -> 2
2 -> 1 -> 3 i.e. 2 -> 3
3 -> 3 -> 1 i.e. 3 -> 1

which, of course, is the same as (1 2 3).

I myself prefer composition on the right, although I can understand why many don't.

#1527 Re: Help Me ! » IQ Test » 2014-12-29 23:08:12

Check the letter positions.

#1528 Re: Help Me ! » IQ Test » 2014-12-26 22:51:33

Yes -- I even give the next two digits in my 'solution' (see the bolded letters).

#1529 Re: This is Cool » Teach Agnishom » 2014-12-26 00:20:48

Try sharpening razors on denim jeans before throwing them out.

And don't let a woman use them to shave her legs.

#1531 Re: Help Me ! » Matrices help » 2014-12-20 11:37:33

For the first question, how would you solve that system of equations if A + B and A - B were numbers, rather than matrices?

For the second, can you combine all of those terms into a single matrix?

For the last question, do you know how to perform Gaussian elimination?

#1532 Re: Maths Teaching Resources » Great Math apps. » 2014-12-18 21:35:54

DeanPemberton wrote:

Math is a subject that is totally based on formulas there are thousands of formulas used in maths, it is not possible to remember all of those formulas you can take help from some apps like Math formulas and Physics formulas.

I'd agree with you at the high-school level, yes; most of the maths I was taught back then was more or less formulaic, and entirely context-driven. But as a subject in and of itself -- and, perhaps even as an art, some might say -- it is built up with axioms, definitions, theorems and proofs. It is certainly not totally based on formulae, and I'm glad that it isn't, because that would sap the fun right out of it for me.

#1533 Re: Help Me ! » difference of zero, circle and alphabet O » 2014-12-14 22:35:26

pari_alf wrote:

Well, i was just considering only in context of shape.
Shape wise they might look similar.
anyway.. thanks guys for having a very nice discussuion

Well, as shapes, they are homeomorphic. We define a homeomorphism as follows.



If f satisfies these conditions, then we say that A and B are homeomorphic.

Intuitively, think about being able to 'continuously deform' one shape into the other.

#1534 Re: Help Me ! » integration problems urgent! » 2014-12-06 00:15:12

bob bundy wrote:

Whoops only ok for x>0.  Back to the drawing board.

Bob

How about f(t) = constant?

#1535 Re: Help Me ! » Can anybody help me with this equation pleaseeee?? » 2014-11-23 07:02:56

Have you been given any other information? What is H?

#1537 Re: Help Me ! » Is there such a function? » 2014-11-11 21:37:43

The Weierstrass function comes to mind, but I think that has a countable number of strict extrema. You might be able to show this via a proof by contradiction (i.e. assuming that there exists an uncountable number of strict extrema).

Of course, the Weierstrass function has no such extrema if they are required to be smooth. I'll have to think about this one.

#1538 Re: Help Me ! » Is there such a function? » 2014-11-11 21:11:30

Agnishom wrote:

I do not get it. What is the period of e^x?

If one extends the definition of exp to the complex numbers, then it is 2πi-periodic, making it very useful for parametrising contours in the complex plane.

#1539 Re: Help Me ! » Euclidean Algorithm Problem » 2014-11-10 03:07:13

Because Alpha is saying that those polynomials are coprime -- but that does not necessarily mean that the evaluations of those polynomials at some number are also coprime.

#1541 Re: Help Me ! » Euclidean Algorithm Problem » 2014-11-09 22:43:11

SolarDevil wrote:

What is the answer to this question?

For how many integers

satisfying
is it true that the fraction
cannot be simplified?

Thanks,
SolarDevil

If that fraction cannot be simplified, then what can you say about the numbers (2n + 7) and (3n - 4)?

What must gcd(3n - 4, 2n + 7) be, in that case? And what does this tell you about the possible values of n? (Hint: Use the Euclidean algorithm.)

#1543 Re: Help Me ! » Integral solutions » 2014-09-02 22:10:27

What does the unique factorisation theorem tell you?

#1545 Re: Help Me ! » How do i find this simple determinent? » 2014-07-22 02:18:07

mrpace wrote:

Can I just assume that the det=1 because it's just a re-arrangment of the identity matrix? Or does the mix up of order affect the determinent? thanks.

The determinant is indeed 1, but you must be careful. Here are some rules about how row (or column) operations affect the determinant of a matrix.

Let the matrix B be obtained from the matrix A by applying the row operation e. Then:

.

These results hold true for the corresponding column operations.

For your matrix, the identity matrix has had two row operations: P(1,4) and P(2,3). So the determinant of your new matrix is (-1)*(-1)*1 = 1.

#1546 Re: Help Me ! » Fraction revelation? » 2014-07-15 07:03:54

Have you encountered partial fractions before?

This is clearly true as you claimed, since

#1548 Re: Help Me ! » Number Daisy and Proof? » 2014-06-12 01:23:58

anonimnystefy wrote:

Hi guys, wouldn't it be better if there was a 20 instead of a 19 there? You can then get up to 47.

How would you make 22 and 24?

#1549 Re: Help Me ! » Sequences » 2014-06-05 22:16:15

For the first question, it might help you to consider the product f(n-1)f(n), and then the product f(n-2)f(n-1)f(n), f(n-3)f(n-2)f(n-1)f(n), etc... you should then get a neat formula for f(2)f(3)...f(n-1)f(n) which can be plugged into your inequality and solved for n.

#1550 Re: Help Me ! » Derivatives » 2014-06-04 18:04:08

You seem to have dropped the differential operator (d/dx) in lines 2 and 3, but otherwise, that looks good to me.

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