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Please help me complete my answer and find the matrix associated to a given quadratic form, here is my work and effort on that


Here's my attempt to answer it



marked as duplicate by amd, Lord Shark the Unknown, Xander Henderson, José Carlos Santos, Namaste Oct 19 '18 at 9:57

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  • $\begingroup$ Again, it would be great if you'd make some effort to write down you work using MathJax. $\endgroup$ – gimusi Oct 18 '18 at 14:08


Recall that for a skew symmetric matrix $S$

$$v^TSv=0 \quad \forall x$$

and that

$$v^T(A+S)v= v^TAv+v^TSv$$

  • $\begingroup$ Thank you for answering my question, but i'm sorry i still don't understand what matrix A and S standing for, are those equal to matrix A and B or B and B'? $\endgroup$ – A.D.P Oct 18 '18 at 14:18
  • $\begingroup$ @A.D.P Do you know what is a skew symmetric matrix? Refer to LINK $\endgroup$ – gimusi Oct 18 '18 at 14:21
  • $\begingroup$ Is it when matrix A' = -A? $\endgroup$ – A.D.P Oct 18 '18 at 14:23
  • $\begingroup$ @A.D.P Yes exactly! $\endgroup$ – gimusi Oct 18 '18 at 14:24
  • 1
    $\begingroup$ okay got it. Thank you so much for your respond :) $\endgroup$ – A.D.P Oct 18 '18 at 14:26

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