Linear Alg Question [closed]

Ok this is for a HW but I'm not looking for a handout...just a hint to get me on the right track.

I have no idea where to begin proving this:

Show that is A is a symmetric matrix, then

x^(t)*A*y = y^(t)*A*x

where ^(t) means transpose.

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You could ask this on math.stackexchange.com; this site is not a good fit for your question. – Mariano Suárez-Alvarez Sep 20 2010 at 15:42
thanks i'll do that – greg Sep 20 2010 at 15:46
Both sides are bilinear forms in $x$ and $y$. So it suffices to plug in $x=e_i$ and $y=e_j$. What happens? – Martin Brandenburg Sep 20 2010 at 15:51