Please help and I would appreciate an explanation as to how you got to the answer.
1.) Solve the system by triangularizing the augmented matrix and using back substitution.
0.09x-0.15y+0.39
-0.18x+0.35y=-0.88
2.) Solve the system by triangularizing the augmented matrix and using back substitution.
-x-y+z=1
x-y-4z=-7
4x+y+z=6
3.) Perform the indicated row operation, then write the new matrix.
-4 4 | 4
9 -6 | 5 -2R1+ R2 ---> R2