Constructing Matrix E and F for RowA and NulA Basis | Homework Explanation

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Homework Statement


Construct a matrix E such that its rows are the basis vectors for rowA and a matrix F such that its columns are the basis vectors for nulA. Compute EF. Explain your results.


Homework Equations


Basis for NulA was { [3 2 1 0], [1 3 0 1] } (except vertical)
Basis for RowA was { [1 0 2 4], [0 1 3 2] } (except vertical)


The Attempt at a Solution


I computed EF and I got the zero matrix, but I'm not sure exactly why this is the case. Can someone provide some insight on this? Thanks.
 
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What is nullspace?
 


NoMoreExams said:
What is nullspace?
Edit: DOH, nevermind, I get it now. The null space is the vectors that get mapped to the zero vector by the matrix. So if you take the matrix's row space and multiply by each of the basis vectors of the nullspace, you will get zero vectors in return (or since it was a matrix of the basis vectors to the null space, you will get the zero matrix in return).
 
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There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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