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Guest Message by DevFuse
 

Rob_Gandy

Member Since 30 Aug 2012
Offline Last Active Jun 06 2013 04:17 PM
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Topics I've Started

Can you find a closed form equation for the sequence?

25 January 2013 - 12:11 AM

This problem recently popped back into my head. In one of my college calculus classes while working on sequences we came across the sequence 0,0,1,1,2,2,3,3,4,4,... and if I remember correctly we were told there was no closed form equation for it. But, I found one and presented it to the class.

a[n]=(2n-1+(-1)n)/4  n=0...infinity

 

My question is: Is there a closed form equation to define the sequence 0,0,0,1,1,1,2,2,2,3,3,3....? If not, why not?

 

Just wondering.  :D


What did I do wrong? (GRE Math)

10 January 2013 - 01:21 AM

How many 3-digit positive integers are odd and do not contain the digit 5? 

 

I got 320, but the answer that is given in 288. I just realized that I missed some numbers, but I ended up with 280.

 

I would greatly appreciate if someone could explain why the answer is 288.


Find the missing numbers in the square.

12 October 2012 - 06:50 PM

2|3|4|15|12
3|4|5|28|20
4|5|6|45|30
5|6|7|66|42
6|7|8| A| B


A=?
B=?
This shouldn't take long. :D

Do you know me?

10 October 2012 - 01:49 AM

I just threw this together so I hope it is alright. :D

The place I am
You do not know
For if you did
You would say so

So sit right down
Let’s play a game
And I will put
You all to shame

I could be near
I could be far
I’ll go by train
Or plane or car

Just a short time
You have to look
To try and find
The thing I took

So start your search
Get on the case
And go to where
The crime took place

You call me evil
You call me vile
I really don’t care
That’s just my style

Now away I go
To plan a heist
And steal a thing
That’s highly priced

So if you think
You can find me
Come have a seat
And we will see

But first things first
Just for my mirth
Find my henchmen
To prove your worth

Do you know me?

Find all the roots.

19 September 2012 - 12:33 AM

I'd say 'Can you find all the roots?,' but I know this will get solved. ^_^


This problem was posted a few years ago in the math department of the college I attended. I got a math club t-shirt and a certificate for getting the correct answer.

Find all the roots of the following equation without the use of technology.:

x6sin(x)+240-14x5sin(x)-308x+69x4sin(x)+22x2-126x3sin(x)+126x3-22x2sin(x)-69x4+308xsin(x)+14x5-240sin(x)-x6=0


Spoiler for Small hint.