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GATE 2022 ES – Question 14

Mathematics Foundation · Linear Algebra · 1 mark · Multiple choice

P is m×n, Q is n×l, R and S are n×n. Assess I:$(PQ)^T=Q^TP^T$; II:$(RS)^{-1}=S^{-1}R^{-1}$.

  1. Both false
  2. I true, II false
  3. Both true
  4. I false, II true

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Correct answer: (C) Both true

Explanation

Transposition reverses multiplication order, so I holds with conformable dimensions. If R and S are invertible, $(RS)(S^{-1}R^{-1})=I$ and the reverse product is I, proving II. Thus **C**, with invertibility implicitly required by the inverse notation.

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