I have managed to do the operation correctly, but I cannot display the Original matrix with the changes, only the change rows. What is missing in my code?

Original matrix after its third row is multiplied by -2:

[ 8. -6. 4. -2.]

Original matrix after exchange of the third row with the sum of itself and first row multiplied by 4:

[ 0. -5. 10. -15.]

Original matrix after exchange of its first and third rows:

[[-4. 3. -2. 1.]

[ 1. -2. 3. -4.]]