Let A be a diagonalizable n × n matrix and let P be an
invertible n × n matrix such that B = P−1AP is the diagonal form of
A. Prove that Ak = PBkP−1, where k is a positive integer. Use the
result above to find the indicated power of A. A = 6 0 −4 7 −1 −4 6
0 −4 , A5 A5 =
Let A be a diagonalizable n × n
matrix and let P be an invertible n × n
matrix such that
B = P−1AP
is the diagonal form of A. Prove that
Ak = PBkP−1,
where k is a positive integer.
Use the result above to find A5
A =
4
0
−4
5
−1
−4
6
0
−6
Let A be some m*n matrix. Consider the set S = {z : Az = 0}.
First show that this is a vector space. Now show that n = p+q where
p = rank(A) and q = dim(S). Here is how to do it. Let the vectors
x1, . . . , xp be such that Ax1, .
. . ,Axp form a basis of the column space of A (thus
each x can be chosen to be some unit...
Let A be an m × n matrix and B be an m × p matrix. Let C =[A |
B] be an m×(n + p) matrix.
(a) Show that R(C) = R(A) + R(B), where R(·) denotes the range
of a matrix.
(b) Show that rank(C) = rank(A) + rank(B)−dim(R(A)∩R(B)).
Let v1 be an eigenvector of an n×n matrix A corresponding to λ1,
and let v2, v3 be two linearly independent eigenvectors of A
corresponding to λ2, where λ1 is not equal to λ2. Show that v1, v2,
v3 are linearly independent.
Let 3x3 matrix A = -3 0 -4
0 5 0
-4 0 3
a) Find the eigenvalues of A and list their multiplicities.
b) Find a basis, Bi, for each eigenspace, E(i).
c) If possible, diagonalise matrix A. (i.e find matrices P and D
such that Pinv AP = D is diagonal).
Let A be a real n × n matrix, and suppose that every leading
principal submatrix ofA of order k < n is nonsingular. Show that
A has an LU-factorisation.
Let A ∈ Mat n×n(R) be a real square matrix.
(a) Suppose that A is symmetric, positive semi-definite, and
orthogonal. Prove that A is the identity matrix.
(b) Suppose that A satisfies A = −A^T . Prove that if λ ∈ C is
an eigenvalue of A, then λ¯ = −λ.
From now on, we assume that A is idempotent, i.e. A^2 = A.
(c) Prove that if λ is an eigenvalue of A, then λ is equal to 0...
Let A be an n × n real symmetric matrix with its row and column
sums both equal to 0. Let λ1, . . . , λn be
the eigenvalues of A, with λn = 0, and with
corresponding eigenvectors v1,...,vn (these
exist because A is real symmetric). Note that vn = (1, .
. . , 1). Let A[i] be the result of deleting the ith row and
column.
Prove that detA[i] = (λ1···λn-1)/n. Thus,
the number of spanning...