math_help

abstract algebra

firepower wrote in math_help May 15, 2011 18:35

I'm trying to understand how to prove an element of an integral domain is irreducible. The book states that 3 is irreducible in the quadratic ring Z[i*√5] because "3*3 = (2 + i√5)(2 - i√5)." Sure, but why does this imply that for every ab=3, either a is a unit or b is a unit? Is this not the definition of irreducible ( Read more... )

question

runnnincircles wrote in math_help May 11, 2011 19:43

If you have a function f: C → C whose modulus is bounded by an nth degree polynomial (call it p), is it correct to assume that the modulus of its derivative is bounded by an (n-1)th degree polynomial? Where by (n-1)th degree polynomial I am not specifically referring to p' but just SOME (n-1)th degree polynomial.

complex variables

Quadratic Equation In Geometry

norain21 wrote in math_help May 10, 2011 16:34

I'm ready to go insane. I have the answers, but nowhere in the book does it tell me how to solve these problems. I've no idea where to begin, and when I try to guess, I get sloppy, wrong answers. Help?

A tennis court has an area of 312yd^2. If the length is 2 yd more than twice the width, find the demensions of the court.

( Read more... )

complex functions

runnnincircles wrote in math_help May 08, 2011 23:24

I am given that f is entire and that f(z+1)= f(z+i) and I am asked to show that f is constant.

I dont see a way to apply Loiusvilles theorem because it doesn't say f is bounded so my feeling is to to try to show that f is constant on some line segment but I dont know which one. Any advice?

upper bound of contour integral

runnnincircles wrote in math_help May 02, 2011 18:40

I am asked to show that |∫ Ce z - z dz| ≤ 60
where C is the positively oriented triangle whose vertices are 0, 3i, -4.

I know that I need to find an upper bound M for e z - z
and that the upper bound for the integral will then be 12M since 12 is the length of C. I am completely lost on how to find M.

Need Textbook Advice

iconoclass wrote in math_help Mar 17, 2011 22:50

Can anyone recommend a combinatorics text that would be helpful for the kinds of brutal combinatorics questions on the GRE Math Subject Test?

Thanks

Properties of Linear Orders

iconoclass wrote in math_help Mar 10, 2011 01:11

What is the name for the linear order property:

(a,a) ∉ R for all a ∈ S (for linear order R on set S)?

anti-reflexivity?

Statistics Problem

corporate wrote in math_help Mar 08, 2011 15:47

for some reason i keep getting stuck on this statistics problem and nothing seems to be giving me the right answer...? help please! thank you so much in advance.

( Read more )

Math GRE Practice Test Question

iconoclass wrote in math_help Mar 04, 2011 17:05

Question: Let g be the function defined on the set of all real numbers by
g(x) = {1 if x is rational and ex if x is irrational ( Read more... )

Hypothetical

chiyo_no_saru wrote in math_help Mar 02, 2011 23:28

Someone is Wrong on the Internet, and I can't figure out the math myself. (It's not for homework or anything, just to prove a point.)

How hard/how fast would you have to hit a 100lb weight with a 7lb bat to lift it off the ground? Assume no shock absorption, air resistance, etc.