perplexus.info :: Numbers : 3 causes 7

3 causes 7 (Posted on 2012-03-10)

Show that if a*n^2 + b*n + c (a, b, and c are integers)is divisible by seven for three consecutive integers, then it is divisible by seven for all integers.

Submitted by Ady TZIDON

Rating: 4.0000 (1 votes)

Solution: (Hide)

It can be easily shown that the integers a, b and c must be multiples of 7 (see Bractal's proof)

Comments: ( You must be logged in to post comments.)

Subject	Author	Date
my error in the officially published solution	Ady TZIDON	2012-04-21 03:06:25
A definition	broll	2012-03-11 01:34:26

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