A 3 by 3 matrix Bis known to have eigenvalues 0, 1, 2. This information is enough to find three of these (give the answers where possible) : (a) the rank of B (b) thedeterminantofBTB (c) theeigenvaluesofBTB (d) the eigenvalues of (B2 + J)-1.

Respuesta :

Answer with Step-by-step explanation:

We are given that a matrix B .

The eigenvalues of matrix are 0, 1 and 2.

a.We know that

Rank of matrix B=Number of different eigenvalues

We have three different eigenvalues

Therefore, rank of matrix B=3

b.

We know that

Determinant of matrix= Product of eigenvalues

Product of eigenvalues=[tex]0\times 1\times 2=0[/tex]

After transpose , the value of determinant remain same.

[tex]\mid B^TB\mid=\mid B^T\mid \mid B\mid =0\times 0=0[/tex]

c.Let  

B=[tex]\left[\begin{array}{ccc}0&-&-\\-&1&-\\-&-&2\end{array}\right][/tex]

Transpose of matrix:Rows change into columns or columns change into rows.

After transpose of matrix B

[tex]B^T=\left[\begin{array}{ccc}0&-&-\\-&1&-\\-&-&2\end{array}\right][/tex]

[tex]B^TB=\left[\begin{array}{ccc}0^2&-&-\\-&1^2&-\\-&-&2^2\end{array}\right][/tex]

[tex]B^TB=\left[\begin{array}{ccc}0&-&-\\-&1&-\\-&-&4\end{array}\right][/tex]

Hence, the eigenvalues of [tex]B^TB[/tex] are 0, 1 and 4.

d.Eigenvalue of Identity matrix are 1, 1 and 1.

Eigenvalues of [tex]B^2+I=(0+1),(1+1),(2^2+1)=1,2,5[/tex]

We know that if eigenvalue of A is [tex]\lambda[/tex]

Then , the eigenvalue of [tex]A^{-1}[/tex] is [tex]\frac{1}{\lambda}[/tex]

Therefore, the eigenvalues of [tex](B^2+I)^{-1}[/tex] are  

[tex]\frac{1}{1},\frac{1}{2},\frac{1}{5}[/tex]

The eigenvalues of [tex](B^2+I)^{-1}[/tex] are 1,[tex]\frac{1}{2}[/tex] and [tex]\frac{1}{5}[/tex]

Q&A Education