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Q.

Let the determinant of a square matrix  A  of order m  be mn ,where m and n satisfy 4m+n=22 and if 17m+4n=93 , det(n.adj(adj(mA)))=3a5b6cthena+bc=

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a

96

b

101

c

109

d

86 

answer is C.

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Detailed Solution

4m+n=22   17m+4n=93

Solving above two equations, we get m=5 and n = 2
 A is a square matrix of order 5 and |A|   = 5-2=3

Now, we know that adj  (KA) =Kn1  adjA, where A is a matrix of order n
adj(mA)=adj(5A)=551(adjA)=54(adjA)

Again, adj  (54adjA)  =(54)4adjA(adjA)=516|A|52.A=51633A

Now, det (nadj(adjmA))=det(2.516.33.A)

=(2.516.33)5detA=25.580.315.3=25.580.316=65.580.311

  a=11,b=80andc=5         a+bc=80+115=86

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