1. Verifying (A): M22=−1
To find the minor M22, remove the 2nd row and 2nd column from matrix A:
M_{22} = \begin{vmatrix} 1 & 1 \\ 2 & 1 \end{vmatrix} = (1)(1) - (1)(2) = 1 - 2 = -1$
*This statement is **TRUE**.*
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### **2. Verifying (B): $A_{23} = 0$**
To find the cofactor $A_{23}$, first find the minor $M_{23}$ by removing the **2nd row** and **3rd column**:M_{23} = 1224 = (1)(4) - (2)(2) = 4 - 4 = 0$
Now, apply the cofactor sign rule A23=(−1)2+3M23:
A23=(−1)×0=0
This statement is TRUE.