00:02
The question acts to use gaussian elimination with partial pivoting to find the solution.
00:11
Since 5 is the biggest number in the first column, so we switch row 3 with row 1.
00:39
Copy other rows.
01:07
So for row 2, we can do 3 times row 1 minus 5 times row 2.
01:17
For row 3, we can do 2 times row 1, minus 5 times row 1, 2 times row 1, 5 times 2.
01:23
Row 3, and for row 4, we can do row 1 minus 5 times row 4.
01:43
Copy row 1, do the elementary rule operation for row 2, row 3, and row 4.
02:12
Since 17 is the biggest number in the second column, so we switch row 3 with row 2.
02:30
Copy row 1 and row 4...