We want to prove that n(n + 1)(n + 2) is divisible by 6 for all natural numbers n.
Proof by induction:
Base case: The formula holds true for n = 1, because
n(n + 1)(n + 2) = 1(2)(3) = 6, which is obviously divisible by 6.
Induction Hypothesis: Assume the formula holds true for n = k.
That is, assume k(k + 1)(k + 2) is divisible by 6.
{We want to prove that (k + 1)(k + 2)(k + 3) is divisible by 6}
But, what does (k + 1)(k + 2)(k + 3) equal?
(k + 1)(k + 2)(k + 3) = (k + 3)(k + 1)(k + 2)
Distribute the (k + 3) over the rest. This gives us
= k(k + 1)(k + 2) + 3(k + 1)(k + 2)
k(k + 1)(k + 2) is divisible by 6 because of our induction hypothesis.
3(k + 1)(k + 2) is divisible by 6 because (k + 1)(k + 2), the product of two consecutive numbers, is divisible by 2 (i.e. product of an odd and even number is an even number).
The sum of two expressions divisible by 6 is divisible by 6, so it follows that (k + 1)(k + 2)(k + 3) is divisible by 6, showing the formula holds true for n = k + 1.
Therefore, by the principle of mathematical induction,
n(n + 1)(n + 2) is divisible by 6 for all natural numbers n.
2007-03-13 21:21:58
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answer #1
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answered by Puggy 7
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At least 1 integer must be divisible by 2, and exactly 1 integer will be divisible by 3. It is either the same integer (divisible by 6) or the product of these 2 integers must be divisible by 6.
2007-03-13 21:01:42
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answer #2
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answered by pjjuster 2
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Adding on to Archknight you get:
m^3 + 3m^2 + 2m
If you notice all the exponents multiply up to 6.
Well if you took m(m+1)(m+2)(m+3) you will notice that all the exponents multiply up to 24 which would give you the divisor for any 4 consecutive integers. So if we can just use proof to provide the reason why the multiplication of the exponents give you the divisor then we're done....I hope this helps.
2007-03-13 21:31:12
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answer #3
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answered by questionallthings 2
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Sorry, but I do not have an answer. I just wish to try to help you get one. Nobody as yet has provided a mathematical proof of this. Sure, it is obviously true, but without that proof, you really haven't done anything. I am sure there is one out there but I am unable to think of it on my own right now. I at least know how it starts.
'm' is a non-negative integer
A product of 3 consecutive integers would be:
m(m+1)(m+2)
Good luck with the rest of the proof!
2007-03-13 21:09:57
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answer #4
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answered by Archknight 2
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dear God, this is so simple!
123
ie, 1*2*3=6, which is divisible by 6
2*3*4=24, divisible by 6
3*4*5=60, divisible by 6
2007-03-13 21:03:23
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answer #5
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answered by TrueWOW 3
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enable First integer = x then 2d integer = x+a million and 0.33 integer =x+2 Product =x(x+a million)(x+2) evaluate a hypothesis that x(x+a million)(x+2) is a diverse of three try approach of induction For x=a million Product =x(x+a million)(x+2) =a million*2*3 =6 a diverse of three enable us to assume it real for x=n i.e n(n+a million)(n+2) is a diverse of three To teach that it is likewise real for x= n+a million for n+a million x(x+a million)(x+2)=(n+a million)(n+a million+a million)(n+a million+2)=(n+a million)(... =(n+a million)(n+2)(n+3)=(n+a million)(n+2)n+(n+a million)(n+2... if (n+a million)(n+2)n is a diverse of three then (n+a million)(n+2)(n+3)=(n+a million)(n+2)n+(n+a million)(n+2)... =diverse of three+n+a million)(n+2)×3 hence (n+a million)(n+2)(n+3) is a diverse of three hence the assumed hypothesis is right that x(x+a million)(x+2), the made of three consecutive integers is divisible via 3
2016-11-25 19:08:48
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answer #6
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answered by Anonymous
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