(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.


9. A square matrix A is said to be nilpotent if A 0 for some integer r 21. Let A, B be nilpotent matrices, of the same size, and assume AB BA. Show that AB and A +B are nilpotent
9. A square matrix A is said to be nilpotent if A 0 for some integer r 21. Let A, B be nilpotent matrices, of the same size, and assume AB BA. Show that AB and A +B are nilpotent
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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...
(10 points)The trace of a square nxn matrix is A, denoted tr(A), is the sum of its diagonal entries; that is, tr(A) = a11+2)2 +433 +: ... + ann (a) Show that tr(AB) = tr(BA) (b) Show that If A similar to B, then tr(A) = tr(B). (10 points) Let A and B are non-zero n x n matrices. (a) Show that N(A) = N(A2). Hint: Let 2 EN(A), show that is also in N(A2) and vice versa. (b) Show...
2 0 If A is a square matrix then A2 = AA. Let A = Find A2 3 1 A2 = (Simplify your answer.)
(1 point) A square matrix A is idempotent if A2 = A. Let V be the vector space of all 2 x 2 matrices with real entries. Let H be the set of all 2 x 2 idempotent matrices with real entries. Is H a subspace of the vector space V? 1. Does H contain the zero vector of V? choose 2. Is H closed under addition? If it is, enter CLOSED. If it is not, enter two matrices in...
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?...
L. Answer True or False. Justify your answer (a) Every linear system consisting of 2 equations in 3 unknowns has infinitely many solutions (b) If A. B are n × n nonsingular matrices and AB BA, then (e) If A is an n x n matrix, with ( +A) I-A, then A O (d) If A, B two 2 x 2 symmetric matrices, then AB is also symmetric. (e) If A. B are any square matrices, then (A+ B)(A-B)-A2-B2 2....
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 A2 = A. Show that AB BA = 0
4. Let A and B be n x n such that B...
6. [20] Let A, B e Cnxn such that A2 = A and B2 = B. Prove that if (A + B)2 = A + B, then AB is the zero matrix 0 Rnxn.
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Lecky Nunber Memnon Cless M 2. Which matrix is not an elementary matrix? 100 100 100 1 1 10 (D). (C). (B). 01 4 001 (A). 0 1 0 00 1 0 1 1 001 3. Which matrix is invertible? 2 3 100 -7 0 3 [1 2 3 (D). 1 2 3 6 4 (C). 0 0 3 3 01 (A). 3 5 9 6 8 18 (B). 004 2 04 4-5a, a-5a...