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------| 1 0 0 |If A= | 2 3 4| And det A = 45 then find x.-------| 5 -6 x| |
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Answer» DET(A)= ∣ ∣ ∣ ∣ ∣ ∣ ∣ ∣
1 2 5
0 3 −6
0 4 x
∣ ∣ ∣ ∣ ∣ ∣ ∣ ∣
=1(3x+24), expand along FIRST row ⇒45=3x+24 ⇒3x=45−24=21 ∴x=7 |
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