Q33 / 124 · NTA Abhyas (JEE Main) 2020 · Mathematics · Determinants

Let A=aij be a square matrix of order 3 and B=bij be a matrix such that bij=2i-jaij for 1≤i,j≤3, ∀i,j∈N. If the determinant of A is same as its order, then the value of BT-1 is

  • Correct answer
    A
    13
  • B
    3
  • C
    9
  • D
    127

Solution

∵A=3
B=a1112a1214a132a21a2212a234a312a32a33
B=8a1112a1214a13a2112a2214a23a3112a3214a33=a11a12a13a21a22a23a31a32a33=A=3
BT-1=1BT=1B=13

Hence, the correct answer is option: 'A'.

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