Q.

Let k be a positive real number and  A=2k12k2k2k12k2k2k1 ,      B=02k1k12k02kk2k0
If  det(adjA)+det(adjB)=106 , then [k/2] is equal to ( where [.] is G.I.F) _______

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answer is 2.

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Detailed Solution

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det  A=(2k1)(4k21)+2k(4kk+2k)+2k(4kk+2k)
 =(2k1)(4k21)+8(2k+1)k =(2k+1)((2k1)2+8k)=(2k+1)3
detB=0  since B is skew symmetric matrix of order 3.
det(adjB)=(detB)2=0 
 (2k+1)6=106
 2k+1=10k=4.5
So, [k/2]=[4.5/2]=2

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Let k be a positive real number and  A=2k−12k2k2k1−2k−2k2k−1 ,      B=02k−1k1−2k02k−k−2k0If  det(adj A)+det(adj B)=106 , then [k/2] is equal to ( where [.] is G.I.F) _______