If \(A = \left( {\begin{array}{*{20}{c}} 1&2\\ 2&3 \end{array}} \right)\) and A2 – kA – I2 = 0, where I2 is the 2 × 2 identity matrix, then what is the value of k?

If \(A = \left( {\begin{array}{*{20}{c}} 1&2\\ 2&3 \end{array}} \right

1.	If \(A = \left( {\begin{array}{*{20}{c}} 1&2\\ 2&3 \end{array}} \right)\) and A2 – kA – I2 = 0, where I2 is the 2 × 2 identity matrix, then what is the value of k?
A.	4
B.	-4
C.	8
D.	-8
Answer» B. -4