text: #1a)
  
  from sympy import *
  init_printing(use_unicode=True)
  from sympy.abc import a,r
  i1,i2,i3,i4,i5=symbols('i1,i2,i3,i4,i5')
  
  A = Matrix([[0,0,0,4*r,5*r,a],
              [r,2*r,0,0,0,a],
              [-r,0,3*r,4*r,0,0],
              [0,-2*r,3*r,0,5*r,0],
              [0,2*r,3*r,4*r,0,a],
              [r,0,-3*r,0,5,a]])
  
  B = Matrix([[0,0,0,4*r,5*r,a],
              [r,2*r,0,0,0,a],
              [1,-1,1,0,0,0],
              [0,0,-1,1,-1,0],
              [0,2*r,3*r,4*r,0,a],
              [r,0,-3*r,0,5,a]])
  
  print("A: \n",A)
  print("rref of A (augmented):\n", solve_linear_system(A,i1,i2,i3,i4,i5))
  
  print("B: \n",B)
  print("rref of B (augmented):\n", solve_linear_system(B,i1,i2,i3,i4,i5))
  