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#1 |
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New Member
Join Date: Mar 07
Posts: 1
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why 2+2 and 2*2 = 4
Hi,
I remember a maths class at school where the teacher spent an entire lesson prooving why 2+2 and 2*2 equals 4 (it was some long formula that took her an hour to write down and explain). Can anyone point me in the direction of where i can find this formula or perhaps its name. many thanks simon |
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#2 |
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Fanatic Member
Join Date: Jun 06
Posts: 881
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Re: why 2+2 and 2*2 = 4
I don't know, but I'm going to take a wild guess that it might have been something along these lines:
1 + 1 = 2 2 + 1 = 3 3 + 1 = 4 2 + 2 = (1 + 1) + (1 + 1) = 1 + 1 + 1 + 1 = 2 + 1 + 1 = 3 + 1 = 4 2 * 2 = (1 + 1) * (1 + 1) = 1 * (1 + 1) + 1 * (1 + 1) = 1 + 1 + 1 + 1 = 2 + 1 + 1 = 3 + 1 = 4 or maybe just this: 2 * 2 = 2 * (1 + 1) = 2 + 2 |
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#3 |
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Frenzied Member
Join Date: Mar 07
Location: Omaha, Nebraska
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Re: why 2+2 and 2*2 = 4
Logophobic has the solution.
However, try proving that 2 is the only number other than 0 in the universe that has this characteristic. Any takers out there?
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Doctor Ed |
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#4 |
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Re: why 2+2 and 2*2 = 4
Sorry, is this homework?
a+b = ab => b = ab - a = a (b-1) => a = b / (b-1) If a is an integer, then b / (b-1) is an integer. The only way that this can be true is if b = 0 or if b divides exactly by b-1. The only non-zero value for which this is true is b=2. If you don't mean for them to be integers, but actually numbers, then any pair such that a = b/(b-1) will do. If you mean "where sum = product", then 1+2+3 = 1*2*3. zaza Edit: if you want to prove that b=2 is the only non-zero value, then let b=2+c. Then 2+c = a+ac and c = 2-a/(a-1). If a<0 then c<0 and b<2. If a=0, c=-2 and b=0. If a=1, then c is undefined. If a=2 then c=0 and b=2. If a>2 then c<0 and b<2.
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I use VB 6, VB.Net 2003 and Office XP ![]() Code: Excel Graphing | Excel Timer | Excel Tips and Tricks | Add controls in Office | Data tables in Excel | Gaussian random number distribution (VB6/VBA,VB.Net) | Coordinates, Vectors and 3D volumes Last edited by zaza; Mar 27th, 2007 at 05:44 PM. |
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#5 | |
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Re: why 2+2 and 2*2 = 4
Quote:
Beacse at the end you can found (1 + 1) + (1 + 1). That is same result.
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