Let J n , m = ∫ 0 1 / 2 x n x m - 1 d x , ∀ n > m and n ,   m ∈ N . Consider a…

Let Jn,m=01/2xnxm-1dx,n>m and n, mN. Consider a matrix A=aij3×3 where aij=J6+i,3-Ji+3,3,  ij0,  i>j. Then adjA-1 is :
  1. (15)2×234
  2. (15)2×242
  3. (105)2×236
  4. (105)2×238

Solution

A=a11a12a130a22a2300a33A=a11a22a33

|A|=J7,3-J4,3·J8,3-J5,3·J9,3-J6,3

=01/2x7-x4x3-1dx·01/2x8-x5x3-1dx·01/2x9-x6x3-1dx

=01/2x4dx·01/2x5dx·01/2x6dx

=1(210)·(2)18

Now

adjA-1=A-12=1|A|2=(210)·2182=(105)2·(2)38

Asked in: JEE Main 2021 (01 Sep Shift 2)

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