In[83]:= a2={{1,0,-1,3,-1},{1,0,0,2,-1},{2,0,-1,5,-1},{0,0,-1,1,0}}; MatrixForm[a2]
a2={{1,0,-1,3,-1},{1,0,0,2,-1},{2,0,-1,5,-1},{0,0,-1,1,0}}; MatrixForm[a2]
Out[83]=
1 0 -1 3 -1 1 0 0 2 -1 2 0 -1 5 -1 0 0 -1 1 0
Up to Exercises