Math Forum / Mathematics / Algebra Help / May 2004

This is a plug for my new weblog called 'think again!' at
http://thinkagain.simpler-solutions.net started today.
It will present a seductive math problem every day. I would appreciate
if some of you paid it a visit, solve the problems, and leave a

Hi! I am an Electronics & Telecommunication Engineering student. Can
you please suggest some web reference on general mathematics or
engineering mathematics?
Thank you.

Are the two symbols below equivalent? Do both of them mean C(n,r)?
( n )   &  n
 r         C
            r

I have this formula:
A = ((B - C)10.68) x B
How could this formula be rewritten to solve for B?  IE I know A and
C.

I thought I got my head round relational algebra until this question came
up....
We have a database with the following relations:
Division([divono],div_name,)

I'm looking for questions that you'd find on the Putnam and of course the
answers to verify my answers.
Thanks

Could someone explain how to find the indefinite integral
Int(Sqrt(Tan(x)) dx, x)?
Thank you.

I have these two problems from classical probability. Any help will be
appreciated.
1. There are n distinct balls and r indistinguishable urns. What is
the probabilty that the ith urn will have a(i) balls. What will be the

f(x) = sqrt(x)
g(x) = x^2
I can look at it and see that the graph is from 0 to 1, but how could I have
done that algrebraically here?  Sorry, I know it is an easy one.

f(x) = x^3 and g(x) = x
interval x=-1, x=0, and x=1
It says, by looking at the graph, we see that neither function is greather
than the other on the interval [-1,1].

Take two equations, please:
First, f(x)=x^2 and f(x)=x^3, I read that x^2 is said to be larger on the
interval [0,1] (they used .5 in each equation.)
Second, f(x)=x^4=2x^2 and g(x)=28-x^2, they said that g(0) > f(0);

y=4(x-2)^2, y=x^2-4x=7, about the y-axis
I first tried 0 to 2 as the bounds and after working the problem found it
should have been 0 to 4, but I do not understand why.  I thought that since
it was rotated about the y-axis and because y is a function of x here that I

Hello, I am attempting to solve the following problem, but am not having much
success.
Problem:
Let (x1, y1) and (x3, y3) denote two points in the Cartesian plane. Given an

I need to find the commutator subgroup of the frobeniusgroup of order
p*(p-1), where p is an odd prime.
So far I have only found a way to show that the commutator group (Let's call
it C) has order p*k where k is a divisor in (p-1)

Hi All!!
I'm an AP Calc teacher and shamefully this integral is stumping me!! Could
any help out?
int(1-arctan(e^t))