Starting with a 4x4 matrix A, the following elementary row operations are performed one after the other. Switch rows 1 and 3. Multiply row 1 by the scalar 1/5. Subtract 8 times row 1 from row 3. Add 9 times row 1 to row 4. Divide row 2 by the scalar 4. Subtract 5 times row 2 from row 4. Switch rows 3 and 4. Add 4 times row 3 to row 4. After doing all this, the matrix is converted into the upper triangular matrix U 1 0 1 1 L- 0 0 9 8 0 0 0 5