Let \(\mathrm{A}=\left[\begin{array}{lll} 2 & \mathrm{a} & 0 \\ 1 & 3 & 1 \\ 0 & 5 & \mathrm{~b} \end{array}\right]\). If A3 = 4A2 – A – 21I, where I is the identity matrix of order 3 × 3, then 2a + 3b is equal to :
1
-10
2
-13
3
-9
4
-12
5
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