Ononot — A real symmetric 4 \times 4 matrix A has eigenvalues -2, 1,

Eigenvalues & Eigenvectorsmedium

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A real symmetric $4 \times 4$ matrix $A$ has eigenvalues $-2, 1, 3, 4$ . For any nonzero vector $x \in \mathbb{R}^4$ , the quadratic form $x^\mathrm{T}Ax$ can be: