Calculate the reduced row echelon form of the following matrices. Approximate answers should be entered to at least 4 decimal places. (You can also enter fractions such as 5/4).
a) (1 2)
(3 4)
b) (1 2 3)
(3 4 9)
c) (3 1 0 4)
(1 5 2 1)
(2 2 4 2)
(2 -4 -2 3)
(3 7 6 3)