document.write( "Question 40403: Proof of Hermitian matrices: If A and B are Hermitian matrices, I need to show that BA = AB iff AB is Hermitian, but I can't figure out how... \n" ); document.write( "
Algebra.Com's Answer #26156 by venugopalramana(3286)\"\" \"About 
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A AND B ARE COMPLEX HERMITIAN MATRICES OF ORDER (N,N)
\n" ); document.write( "LET TRANSPOSE OF A AND B BE A' AND B'
\n" ); document.write( "SINCE A,B ARE HERMITIAN,WE HAVE
\n" ); document.write( "A=CONJUGATE (A') AND B= CONJ(B')……………………….I
\n" ); document.write( "CASE 1.
\n" ); document.write( "AB IS HERMITIAN.LET AB=C…..SO AB=C=CONJ(C')=CONJ(AB)'…………..II
\n" ); document.write( "C'=(AB)'=B'A'
\n" ); document.write( "CONJ(C')=CONJ(B'A')=CONJ(B')CONJ(A')=BA…FROM I
\n" ); document.write( "BUT AB=CONJ(C') FROM II
\n" ); document.write( "SO AB=BA
\n" ); document.write( "CASE 2.
\n" ); document.write( "AB=BA= CONJ(B')CONJ(A')=CONJ(B'A')=CONJ(AB)'=AB…..
\n" ); document.write( "HENCE AB IS HERMITIAN.
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