
Linear Algebra Linear Algebra Math Forum 
 LinkBack  Thread Tools  Display Modes 
September 2nd, 2009, 05:31 PM  #1 
Newbie Joined: Sep 2009 Posts: 6 Thanks: 0  If A and B are symmetric, show A+B is also symmetric
Here's how the problem reads: Let A and B be symmetric matrices. a) Show that A+B is symmetric. b) Show that AB is symmetric if and only if AB=BA. 
September 3rd, 2009, 06:51 AM  #2 
Senior Member Joined: Feb 2009 Posts: 172 Thanks: 5  Re: If A and B are symmetric, show A+B is also symmetric
a) Since , and you have that . That is, is symmetric. b) Suppose that is symmetric. Then you have that . But . Hence, . Suppose . Since and you have that that is, is symmetric. 

Tags 
show, symmetric 
Thread Tools  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
symmetric to what axis  kkelley  Algebra  0  May 27th, 2012 05:13 AM 
Symmetric group S4  andmar  Abstract Algebra  3  October 8th, 2011 10:48 AM 
For a curve to be symmetric?  jaredbeach  Algebra  2  August 19th, 2011 04:41 AM 
Symmetric Operator  Nusc  Real Analysis  4  March 24th, 2009 12:34 PM 
Symmetric Groups  501622731  Abstract Algebra  1  March 24th, 2009 09:22 AM 