How about doing rowops to get
ac bc
ac ad
And subtract
I need to prove if ad-bc=/=0 then the reduced row echelon from of matrix
a b
c d
is
1 0
0 1
I have the cases where
1) a,b,c,d =/= 0
2) a = 0, b,c =/= 0
3) b = 0, a,d =/= 0
4) c = 0, a,d =/= 0
5) d = 0, b,c =/= 0
Close? Or what? Thanks.