Answer
Fill blanks with:
... 3 ...
... second ...
... $-2$ ...
... third ...
Work Step by Step
To obtain a zero in the position (2,1),
(row 2, column 1, where the current element is $-3$)
multiply the element 1 in row 1 by 3 and add it to -3 (in the second row).
So, the first two blanks are filled with
... 3 ...
... second ...
To obtain a zero in the position (3,1),
(row 3, column 1, where the current element is $2$)
multiply the element 1 in row 1 by $-2$ and add it to $2$ (in the third row).
So, the last two blanks are filled with
... $-2$ ...
... third ...