Q18 of 127 Page 131

If A is an invertible matrix of order 2, then det (A–1) is equal to



{since adj(A) is of order n and |Adj(A)| = |A|n-1}


Alternative-


We know that AA-1 = I


So |A||A-1| = |I| = 1


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If a = [ ccc 2&-1&1 -1&2&-1 1&-1&2 ]Verify that A3 – 6A2 + 9A – 4I = O and hence find A-1.

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Let A be a non-singular square matrix of order 3 × 3. Then |adj A| is equal to

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Examine the consistency of the system of equations.

x + 2y = 2


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