row-echelon

1   -2    0    0   3
2   -5   -3   -2   6
0    5   15   10   0
2    6   18    8   6

((row 2) - ((row 1) *2))*-1
1   -2    0    0   3
0    1    3    2   0
0    5   15   10   0
2    6   18    8   6

(row 3) - ((row 2)*5)
1   -2    0    0   3
0    1    3    2   0
0    0    0    0   0
2    6   18    8   6

I have tried many many ways of getting the last row to all zero 
(as required by row-echelon, not reduced row-echelon) but cant
figure it out