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Sum Square Grid Row & Column ≠ 0 (Posted on 2010-04-29) Difficulty: 3 of 5
Each cell of a 1997x1997 square grid contains either +1 or -1, with no cell being vacant.

The product of all the numbers in the ith row, and the product of all the numbers in the ith column are respectively denoted by Ri and Ci.

               1997
Prove that  Σi=1(Ri + Ci) is always nonzero.

No Solution Yet Submitted by K Sengupta    
Rating: 2.0000 (2 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
re: a simple proof | Comment 4 of 6 |
(In reply to a simple proof by Ady TZIDON)

I think you misread the problem, you have Ri and Ci as the sum of the row/column where in fact they are the products of the row/column.
  Posted by Daniel on 2010-04-29 15:29:54

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