A rectangular game board is composed of identical squares arranged in a rectangular array of r rows and r+1 columns.The r rows are numbered from 1 through r, and the r+1 columns are numbered from 1 through r+1. If r >10, which of the following represents the number of squares on the board that are neither in the 4th row nor in the 7th column? r平方-r r平方-1 r平方 r平方+1 r平方+r
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发表于 2012-7-7 01:36:02
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