4. Let A and B be n x n such that B = 1-A and A2 = A. Show that AB BA = 0 4. Let A and B be n x n such that B 1-A and A2 = A. Show that AB-BA-0 4. Let A and B be n x n such that B = 1-A and...
please show steps
Let 0 a12 a13 a14 0 a34 a42 023 a43 0 a14 a31 a24 a41 0 a12 a32 a13 a21 0 a21 0 a2 a2 a31 a32 0 a34 be two antisymmetric matrices, where ak -aki, or ATA and BT -B. Show that AB BA and present this diagonal matrix as follows BA AB (a32014 +a13024 a21a34) I, where I is the 4 x 4-identity matrix. Find A-1 and B-1. (H. Minkowski, 1908)
Let 0 a12 a13...
(c) If A is a square matrix and A2 = 0,then A = 0. (d) Let A, B be two square matrices. If (A + B) 2 = A2 + 2AB + B2 , then AB = BA.
8. Let An be the following n x n tridiagonal matrix ab 0 0 0 Cab 00 0 0 Oca 0 0 0. 0 0 0 C a Show that AnalAn- 1l-bc|A,-21 for n 2 3. If a = 1+bc, show that |An 1+bc+ (be)2 ++(bc)" If a 2 cos with 0 <0<T and b c 1 then show that sin (n+1)0 |An = sin 0 nn change
8. Let An be the following n x n tridiagonal matrix ab...
4. Let A be an n x n matrix. Define the trace of A by the formula tr(A) = 2 . In other words, the trace of a matrix is the sum of the diagonal entries of the matrix. It is known that for two n x n matrices A and B, the trace has the property that tr(AB) = tr(BA). Each of the following holds more generally, for n x n matrices A and B, but in the interest...
1. Let a and b be elements of a group
. Prove that ab and ba have the same order.
2. Show by example that the product of elements of nite order in a
group need not
have nite order. What if the group is abelian?
Let A and B be n × m, and m × n matrices over F respectively. Prove that rn ) = det(In-AB) = det(I,n-BA). In det A
Let A and B be n × m, and m × n matrices over F respectively. Prove that rn ) = det(In-AB) = det(I,n-BA). In det A
4. Let A and B be two nx n matrices. Suppose that AB is invertible. Show that the system A.x = 0 has only the trivial solution.
Let n > 1. Consider the monoid D2n = mn〈 a, b ∣ a2 = 1, bn = 1, ab = bn−1a 〉, n > 1. Prove that the presentation is Church–Rosser and defines a group of order 2n. Show that D2n is isomorphic to the group of all symmetries of the regular n-gon on the plane. This is the so-called dihedral group of order 2n.
5. Find a 2 x 2 matrix A such that A2 = I2, but A + +12. (Hint: you can do this algebraically, or geometrically.) For all the remaining questions, let n > 2 and let A and B be n x n matrices. 6. Does the equation A(B – In) + (In – B)A = On,n always hold? Either prove it or give a counter-example. 7. If A and B are invertible, does that imply that AB is invertible?...
P.2.16 Let V= span {AB-BA : A, B E Mn. (a) Show that the function tr : M,,-> C is a linear transformation. (b) Use the dimension theorem to prove that dim ker tr = n2-1. (c) Prove that dim V = n2-1. (d) Let Eij=eie), every entry of which is zero except for a 1 in the (i, j) position. Show that k,-OikEil for l i, j, k, n. (e) Find a basis for V. Hint: Work out the...