As we know ,there are three different elementary transformations of matrix, they are "change two distinct rows", "multiply a non-zero number to a row of the matrix","add a k times of a row to another row,where k is a number in the field and non-zero".

Obviously,we can use the last two to get the first elementary transformation("change two distinct rows"), so whether the first elementary transformation is unnecessary?

Another question is : what is the geometric meaning of these elementary transformations of matrix?