Let A and B be 4 x 4 matrices, with det(A) = 3 and det(B) = 5. Compute: 1. det(AB) – det(BA) 2. det(A²)+det(B2) 3. det(2A3B) 4. det(ATBA) 5. det(B-1AB)

Respuesta :

We have

[tex]\det(AB)=\det A\det B[/tex]

for any two matrices [tex]A,B[/tex], and

[tex]\det A^{-1}=\dfrac1{\det A}[/tex]

[tex]\det A^\top=\det A[/tex]

[tex]\det(kA)=k^n\det A[/tex]

where [tex]k[/tex] is a constant and [tex]n[/tex] is the size of the matrix [tex]A[/tex].

1. [tex]\det(AB)-\det(BA)=\det A\det B-\det B\det A=0[/tex]

2. [tex]\det(A^2)+\det(B^2)=(\det A)^2+(\det B)^2=34[/tex]

3. [tex]\det(2A^3B)=2^4\det(A^3B)=16(\det A)^3\det B=2160[/tex]

4. [tex]\det(A^\top BA)=\det A^\top\det B\det A=45[/tex]

5. [tex]\det(B^{-1}AB)=\dfrac1{\det B}\det A\det B=\det A=3[/tex]