Show that one and only one out of n( n+1 ) and (n+2 ) is divided by 3 , where n is any positive integer.
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Step-by-step explanation:
Since n, n+1, n+2 are three consecutive integers then there must be one number divisible by 3 at least.
If the remainder at dividing n by 3 is 1, then n+2 must be divisible by 3 and if the remainder at dividing n by 3 is 2, then n+1 must be divisible by 3. Similarly for n+1 and n+2.
Let n be divisible by 3.
(n+1)/3=n/3+1/3,
Now, n is divisible by 3 but 1 is not. So we get n+1 not divisible by 3. Similarly,n+2 will not be divisible by 3 as well if n is divisible by 3.
(n+2)/3=n/3+2/3,
In the same way, if n+1 is divisible by 3 then n and n+2 can't be divisible by 3. If n+2 is divisible by 3 then n and n+1 cannot be divisible by 3.
Hope it helps.
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