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  #1  
Old 03-12-2006, 05:04 PM
Mr. Curious Mr. Curious is offline
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Default Basic math proof

If there a theorum or proof about the following?

The difference between the squares of two consecutive numbers is the sum of those numbers.

For instance:

4^2 - 3^2 = 3 + 4
16 - 9 = 7
7 = 7

10^2 - 9^2 = 9 + 10
100 - 81 = 19
19 = 19

btw - This works for both positive and negative, though it needs to be modified a bit for negative numbers to work correctly because of the negative sign.
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  #2  
Old 03-12-2006, 05:20 PM
Kerth Kerth is offline
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Default Re: Basic math proof

x^2 - (x - 1)^2 = x + (x - 1)
x^2 - (x^2 - 2x + 1) = 2x - 1
2x - 1 = 2x -1
0 = 0
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  #3  
Old 03-12-2006, 05:28 PM
uDevil uDevil is offline
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Default Re: Basic math proof

Just a little algebra:

n^2-(n-1)^2=n^2-(n^2-2n+1)=n^2-n^2+2n-1=2n-1= n+n-1=n+(n-1)

If n=4, 4^2-(4-1)^2=4+(4-1), or 4^2-3^2=4+3

Edit: Kerth is speedier than I am. [img]/images/graemlins/smile.gif[/img]
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  #4  
Old 03-12-2006, 08:38 PM
Mr. Curious Mr. Curious is offline
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Default Re: Basic math proof

Heh, I meant the name of it (if there is one).
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  #5  
Old 03-12-2006, 11:05 PM
Nottom Nottom is offline
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Default Re: Basic math proof

[ QUOTE ]
Heh, I meant the name of it (if there is one).

[/ QUOTE ]

Its just a neat observation, hardly worthy of a name.
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  #6  
Old 03-12-2006, 11:43 PM
Mr. Curious Mr. Curious is offline
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Default Re: Basic math proof

[ QUOTE ]
[ QUOTE ]
Heh, I meant the name of it (if there is one).

[/ QUOTE ]

Its just a neat observation, hardly worthy of a name.

[/ QUOTE ]

I suppose. I thought of it back in the 8th grade (21 years ago) and my math teacher at the time blew it off. I remembered it again a couple of days ago and posted it to see if mattered.
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  #7  
Old 03-13-2006, 12:53 AM
bigt2k4 bigt2k4 is offline
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Default Re: Basic math proof

deleted
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  #8  
Old 03-13-2006, 02:49 AM
uDevil uDevil is offline
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Default Re: Basic math proof

[ QUOTE ]
[ QUOTE ]
[ QUOTE ]
Heh, I meant the name of it (if there is one).

[/ QUOTE ]

Its just a neat observation, hardly worthy of a name.

[/ QUOTE ]


I suppose....

[/ QUOTE ]


How about the "Curious-Kerth theorem"? C-K for short.
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  #9  
Old 03-13-2006, 03:12 AM
drbst drbst is offline
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Default Re: Basic math proof

LOL, every child in the 7th grade knows that (a-b)*(a+b) = a^2-b^2.

Do you really think the special case of a=b+1 should be called a "theorem"?

Try this: add the first n odd numbers (1, 1+3, 1+3+5, 1+3+5+7, ...) and see if you can find a pattern. Explain. [img]/images/graemlins/laugh.gif[/img]
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