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 singular. geo
Proof
It follows from Diagonalization of a quadratic form away from 2.
Away from 2 a projective quadric is singular iff its corresponding matrix is singular. geo
Proof
It follows from Diagonalization of a quadratic form away from 2.