[[Projective quadric]]
# A quadric is singular iff its matrix is singular away from 2

[[Away from 2]] a [[projective quadric]] is singular iff its corresponding matrix is [[Types of square matrix|singular]]. #m/thm/geo 

> [!check]- Proof
> It follows from [[Diagonalization of a quadratic form away from 2]].
> <span class="QED"/>
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