Find the determinant of

det(A)=

The determinant of A is the sum of the entries in ANY row or column of A multiplied by their respective cofactors. In this case, let’s choose column 4 because there are three zero entries in the first, second, and third rows of the fourth column.

The determinant of

Since a_{14}, a_{24}, and a_{34} are
all equal to 0 à |A|=a_{44}C_{44}

C_{44}=(-1)^{4+4}M_{44}=1*2=2

|A|=a_{44}C_{44}=2*2=4