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Please answer from (b) to (e) 1. Fill in the blank. No partial credit! (2 pts ea

ID: 3138487 • Letter: P

Question

Please answer from (b) to (e)

1. Fill in the blank. No partial credit! (2 pts each) atristhat satisfies the equaticn Al::??:1.then the dete (a) Let A be 2 x 2 matrix that satisfies the equation A minant IA- (b) {?a, 0, b, 1] | a, b E R} is a subspace of R4 (c) Let A, D and P be n × n matrices such that A-PDP-1. Then D: Solve for D in terms of the other two matrices) (d) Consider the matrix equation Av-w where 4 is an eigenvalue of the invertible matrix A and v . It follows that an eigenvalue of A-1 is (e) A harmonic oscillator z + br + x = 0 is critically damped when

Explanation / Answer

(b). Let the given set be denoted by S and let X = (a,0,b,1) and Y = (c,0,d,1) be 2 arbitrary vectors in S. Then X+Y = (a,0,b,1)+(c,0,d,1)= (a+c,0,b+d,2). It implies that X+Y ? S. Hence S is not closed under vector addition, and, therefore, S is not a subspace of R4.

(c ). If A = PDP-1, then AP = (PDP-1)P= PD(P-1 P) = PD In =PD and then P-1 AP =P-1(PD) = (P-1P)D = In D = D. Hence D = P-1 AP.

(d).We know that a matrix A has an eigenvalue ? if and only if A-1 has eigenvalue 1/?. Thus, if 4 is an eigenvalue of A, then ¼ is an eigenvalue of A-1.