1. Which set of three-by-one matrices (with real number scalars) is not a vector space? The set of three-by-one matrices with zero in the third row. The set of three-by-one matrices with the first row...

Extracted text: 1. Which set of three-by-one matrices (with real number scalars) is not a vector space? The set of three-by-one matrices with zero in the third row. The set of three-by-one matrices with the first row one larger than the third row. The set of three-by-one matrices with the sum of all the rows equal to zero. The set of three-by-one matrices with the first row equal to the negative of the third row.