Algebra 2 (1st Edition)

$57$
For a 3x3 matrix: $\left[\begin{array}{rrr} a & b & c \\ d &e & f \\ g &h & i \\ \end{array} \right]$ The determinant is given by: $D=a(ei-fh)-b(di-fg)+c(dh-eg).$ Hence here $D=5(2\cdot1-1\cdot1)-(-9)(4\cdot1-1\cdot0)+4(4\cdot1-2\cdot0)=5(1)+9(4)+4(4)=57.$