Answers:

1. Determinant of = a₁₁a₂₂ - a₂₁a₁₂ = 1*4 - 2*3 = -2

2. Determinant of = a₁₁det(M₁₁) - a₁₂det(M₁₂) + a₁₃det(M₁₃)

M₁₁ = , M₁₂ =, M₁₃ =

det(M₁₁) = 5*(-9) - 2*10 = -65

det(M₁₂) = 3*(-9) - 7*10 = -97

det(M₁₃) = 3*2 - 5*7 = -29

 determinant of = 2(-65) - (-97) + (-6)(-29) = 141