Answer:
(a) a=6 and b≠
(b)a≠6
(c) a=6 and b=
Step-by-step explanation:
writing equation in agumented matrix form

now 

now 

a) now for inconsistent
rank of augamented matrix ≠ rank of matrix
for that a=6 and b≠
b) for consistent w/ a unique solution
rank of augamented matrix = rank of matrix
a≠6
c) consistent w/ infinitely-many sol'ns
rank of augamented matrix = rank of matrix < no. of variable
for that condition
a=6 and b=[tex]\frac{11}{4}
then rank become 3 which is less than variable which is 4.