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.
Prove that Σi=1(Ri + Ci) is always nonzero.
(In reply to re: Solution - (MS Word Formatting!?)
It's best to use a text editor, such as Notepad, rather than a word processor, such as Word.
word processors have much embedded, invisible formatting stuff that gets carried over, not conducive to any method of entry in the comments.
Posted by Charlie
on 2010-04-30 02:17:37