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JEE Main Mathematics Matrices 2026 JEE Main 2026 (24 January Shift 2)

JEE Main Mathematics Question (2026) — Solution

Question

Let P= [p_ i j ] and Q= [q_ i j ] be two square matrices of order 3 such that q_ ij =2^ ( i + j -1) p _ ij and det ( Q )=2^ 10 . Then the value of det ( adj ( adj P )) is:

Options

  1. A. 81
  2. B. 16
  3. C. 124
  4. D. 32

Answer

B. 16

Step-by-step solution

vmatrix 2p_ 11 & 2^2p_ 12 & 2^3p_ 13 \\ 2^2p_ 21 & 2^3p_ 22 & 2^4p_ 23 \\ 2^3p_ 31 & 2^4p_ 32 & 2^5p_ 33 vmatrix = 2^ 10 2^2 2 2^3 vmatrix p_ 11 & p_ 12 & p_ 13 \\ 2p_ 21 & 2p_ 22 & 2p_ 23 \\ 2^2p_ 31 & 2^2p_ 32 & 2^2p_ 33 vmatrix = 2^ 10 2^9 vmatrix p_ 11 & p_ 12 & p_ 13 \\ p_ 21 & p_ 22 & p_ 23 \\ p_ 31 & p_ 32 & p_ 33 vmatrix = 2^ 10 |P| = 2 | adj ( adj (P))| = |P|^ (n-1)^2 = |P|^4 = 2^4 = 16

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