3-r1-r2,r2-2r1,r4-r1
1 1 -2 3 0
0 -1 -2 -2 -1
0 0 a+8 0 0
0 -2 -4 -4 b
r4-2r2
1 1 -2 3 0
0 -1 -2 -2 -1
0 0 a+8 0 0
0 0 0 0 b+2
当a=-8,b=-2时,r(A)=2
当a≠-8,b=-2,或 a=-8,b≠-2 时,r(A)=3
当时a≠-8,b≠-2时,r(A)=4.
3-r1-r2,r2-2r1,r4-r1
1 1 -2 3 0
0 -1 -2 -2 -1
0 0 a+8 0 0
0 -2 -4 -4 b
r4-2r2
1 1 -2 3 0
0 -1 -2 -2 -1
0 0 a+8 0 0
0 0 0 0 b+2
当a=-8,b=-2时,r(A)=2
当a≠-8,b=-2,或 a=-8,b≠-2 时,r(A)=3
当时a≠-8,b≠-2时,r(A)=4.