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If A is a 3 × 3 matrix and det(A) = 5, then det(2A) is
A40
B10
C5
D20
Answer & Solution
Correct answer: A. 40
1. For an n × n matrix det(kA) = k^n det(A).
2. Here n = 3 and k = 2 so factor is 2³ = 8.
3. det(2A) = 8 × 5 = 40.
_Source: Maharashtra Balbharati Std XII Mathematics Part 1, Ch 2 "Matrices" §2.5_
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