Q.

Match the following columns:

  Column I (A,B,C are matrices)   Column-II
a. If |A3×3|=2, then |2A-1|= p. 1
b. If |A3×3|=18, then |adj(adj(2A))|= q. 4
c. If (A+B)2=A2+B2, and |A2×2|=2, then |B2×2|= r. 8
d. |A2×2|=2,|B3×3|=3 and |C4×4|=4, then |ABC| is equal to s. 0
    t. Does not exist

 

1 a-q; b-p; c-s; d-t  
2 a-p; b-r; c-q; d-s  
3 a-p; b-q; c-r; d-s  
4 a-s; b-q; c-r; d-p  

Ans.

(1)

a. |A|=2⇒|2A-1|=23/|A|=4

b. |adj(adj(2A))|=|2A|4=212|A|4=212/212=1

c. (A+B)2=A2+B2⇒AB+BA=O

    ⇒|AB|=|-BA|=-|BA|=-|AB|⇒|AB|=0⇒|B|=0

d.  Product ABC is not defined.