Math Is Fun Forum
You are not logged in.
- Topics: Active | Unanswered
#51 2012-12-21 23:21:42
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Creating Functions?
Hi;
Okay, I am glad to help.
About catching up, I recommend you post your questions here when you get stuck. There are knowledgeable people here.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
Offline
#52 2012-12-21 23:40:10
- therussequilibrium
- Member
- Registered: 2012-12-21
- Posts: 36
Re: Creating Functions?
Okay, maybe it was easier than I thought to simplify, I think I figured it out. I just wasn't sure if I should distribute first or FOIL first. And what I ended up with was this:
And it seems like you can divide, which seems weird, but it comes out with the right answer.
So, it seems that I can divide like that, and I simplified correctly?
Offline
#53 2012-12-21 23:42:10
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Creating Functions?
Hi;
That is correct. Do not forget to add them up to make the formula.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
Offline
#54 2012-12-21 23:44:55
- therussequilibrium
- Member
- Registered: 2012-12-21
- Posts: 36
Re: Creating Functions?
Awesome! Again thanks for your help! And I will definitely do what you suggested, I plan on devoting a lot of my time to math from here on so I'll probably be here often.
Thanks again!
Offline
#55 2012-12-21 23:46:58
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Creating Functions?
Hi;
You are welcome. Have a good holiday.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
Offline
#56 2012-12-26 03:31:31
- Bob
- Administrator
- Registered: 2010-06-20
- Posts: 10,621
Re: Creating Functions?
hi therussequilibrium
Finally remembered that formula and another way to prove it.
You can use a similar method for any summation of the form
Let's say you have spotted that the formula you want is
Start with the next highest power of n, ie. n cubed.
Write out this expression for n=1, n=2, n=3, ...n=n
............... ............ .............. ............. .............
__________________________________________________________________
Now add up each column. Most of the cube terms on the LHS cancel with most of those on the RHS. 1+1+1...+1 comes to n.
The formula for the {triangle numbers} is
so
Re-arranging
multiply by 2 to remove the fraction and factorising out the common factor of (n+1)
and so, finally
Bob
Children are not defined by school ...........The Fonz
You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you! …………….Bob 
Offline