Let A be an matrix with entries in . Show by using elementary row and column operations, that there are invertible matrices P and Q (where P has size and Q has size ) such that:

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I can sort of see why this is true. You would need to use ECO's to make all but 1 entries in a row 0, and then permute the rows until you get the requied order. But I can't see how I can present this in the form of a solution. Help anyone?