Q13 of 256 Page 7

If A = [aij] is a 3 × 3 diagonal matrix such that a11 = 1, a22 = 2 and a33 = 3, then find |A|.

Since A is a diagonal matrix, therefore, all it’s non-diagonal members are 0. And a11=1, a22=2 and a33=3

We get


Then,


Expanding along R1


|A|= 1(2×3-0)=6


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