[Maxima] 2 basic questions about linear.

[test]

1. elementary row operation for "matrix".
     I would like to perform elementary row operation for Matrix.
     [ 1, 1,  2]    first Row of Matrix A  -> Row1
     [ 2, 4, -3]    2nd Row of Matrix A  -> Row2
     [ 3, 6, -5]    3rd Row of Matrix  A -> Row3
   In this Matrix named "A",   I plan to perform Row2 + (-2)*Row1.
   Row(A, 2) - 2*(Row(A,1)  is work well.
   But I can not return the value to Row2 of Matrix A.
   I know the Matrix( [ 1, 0, 1],  [-2, 1,0], [0,  0, 1]).A is good 
another way.
  But I want know how to do.

2. About a norm of vector.
    I try to find the function that return the norm of  a vector.
   But I don't find. So I have done like bellows.

   B:[2,2]
   ABS(B.B)

   That's I performed. Is there any simple way to get a norm of vector
   like ||B|| or Norm(B).

Thank you.