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Unformatted text preview: MAS 3105 Dec 10, 2008 Final Exam and key Prof. S. Hudson 1) (10pts) Suppose A is nxn, real, and skewsymmetric (so, A T = A ). Show that: a) A is normal. b) If n is odd, A must be singular. 2) (10 pts) a) Find the least squares solution to A x = b , using this QR factorization: A = 1 2 1 2 1 2 4 2 4 = 1 5 1 2 4 2 1 2 2 4 2 4 2 1 5 2 1 4 1 2 where b =  1 1 1 2 2b) Let S = R ( A ) and use part a) to find proj S b . 3) (10pts) Choose ONE (a fairly short proof) a) State and prove the Spectral Theorem b) If Y V is a subspace, then so is Y . c) If A and B are nonsingular, then so is AB (state and prove a formula for its inverse). 4) (10pts) Factor A into XDX 1 where D is diagonal (compute the 3 factors  and Id suggest checking them by multiplication). A = 2 8 1 4 5) (10pts) Let S R 3 x 3 be the vector space of all symmetric 3x3 matrices. Find dim(S) and explain briefly....
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This note was uploaded on 12/26/2011 for the course MAS 3105 taught by Professor Julianedwards during the Spring '09 term at FIU.
 Spring '09
 JULIANEDWARDS

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