Final answer:
The echelon form of a matrix is not unique, but the reduced echelon form is. The pivot positions in a matrix do not depend on row interchanges during the row reduction process.
Step-by-step explanation:
The statement 'The echelon form of a matrix is unique' is false. The echelon form of a matrix is not unique because different sequences of row operations can lead to different echelon forms. However, the reduced echelon form of a matrix, which is also known as row reduced echelon form (RREF), is unique for a given matrix.
Regarding pivot positions, the statement that the pivot positions in a matrix depend on whether row interchanges are used in the row reduction process is false. Pivot positions are determined completely by the positions of the leading entries in the nonzero rows of any echelon form obtained from the matrix. These pivot positions do not change even when row interchanges are used.
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