0
$\begingroup$

Does $A\in R^{3\times3}$ with first row $\pmatrix {1&2&3} $ exist (?), if...

  • $A$ can be inverted and
  • one of its eigenvalues is zero
  • 2 Answers 2

    6

    If $A$ has an eigenvalue of zero, then it necessarily cannot be inverted (that is, $A$ is singular). So, the answer is no.

    4

    Nope. A square matrix is invertible iff zero is not one of its eigenvalues, as otherwise its kernel's dimension (the matrix's nullity) is bigger than zero