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Math Help - conditions for the null-space of a matrix to contain only the zero-vector?

  1. #1
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    conditions for the null-space of a matrix to contain only the zero-vector?

    In my linear algebra book, they state that the only way for the null space of a matrix to contain just the zero-vector, the column vectors of the matrix has to be linearly independent, and the matrix has to be a square matrix.

    Now, I understand why the column vectors of the matrix have to be linearly independent, but why does it have to be a square matrix?

    Would appreciate any explanation!
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  2. #2
    Senior Member Tinyboss's Avatar
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    That doesn't seem right to me. The matrix just can't be wider than it is tall (which is already implied by requiring the columns to be independent). Are you sure we're not also requiring something else, like surjectivity?
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    MHF Contributor Bruno J.'s Avatar
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    I agree with Tinyboss, your book is completely wrong. Unless you overlooked something in the statement, I would get another book if I were you. What book is it?

    I would suggest this book: http://www.amazon.com/Linear-Algebra.../dp/0130084514.
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