Quadric surface question, given 3x3 matrix A and (x^T)Ax=6

[imsleepy]

this is my working out:

http://i.imgur.com/1hsQS.jpg

i sort of figured out how to do this a few mins ago lol. it doesn't seem too hard.
it's sort of like... multiplying the first number in the matrix A by it's position in the matrix (x1 * x1) which is basically the coordinates of the value, then doing that for all numbers in the matrix A.

am i right? have i fully answered the question?

edit: in my working out, the x^TAx = sigma sigma axx was taken from my course manual.

 

[lanedance]

haven't followed it all through, but i think you have the right idea

the sigma sigma is just matrix multiplication

 

[imsleepy]

awesome, thank you :)