Let A=[aij]3×3, B=[bij]3×3, where bij=3i−jaij and C=[cij]3×3, where cij=4i−jbij be any three matrices. If det.A = 2 then ‘det.B + det.C’ is equal to
4
We have det.B = det.C = det.A = 2, because det.B = ∣∣ ∣ ∣∣a11a123a1393a21a2213a239a313a32a33∣∣ ∣ ∣∣
=19⋅13∣∣ ∣∣9a113a12a139a213a22a239a313a32a33∣∣ ∣∣
=19⋅13⋅3⋅9∣∣ ∣∣a11a12a13a21a22a23a31a32a33∣∣ ∣∣
=|A|=2
Similarly, det. C = det. B = |A| = 2
Hence, det. B + det. C = 4