|A| = a[1][1]*a[2][2]*a[3][3]+a[2][1]*a[3][2]*a[1][3]+a[3][1]*a[1][2]*a[2][3]
-a[1][1]*a[3][2]*a[2][3]-a[3][1]*a[2][2]*a[1][3]-a[2][1]*a[1][2]*a[3][3]