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Linear AlgebraEasySymmetric Matrices & Quadratic Forms

Symmetric Matrices & Quadratic Forms · Easy problem

Let AA be the symmetric 3×33\times 3 matrix with q(x,y,z)=x2+2y2+3z2+4xy−2yz=xTAxq(x,y,z) = x^2 + 2y^2 + 3z^2 + 4xy - 2yz = \mathbf x^{T}A\mathbf x. Find the sum of all nine entries of AA.