Consider the matrix A=(210121012)A = \begin{pmatrix} 2 & 1 & 0 \\ 1 & 2 & 1 \\ 0 & 1 & 2 \end{pmatrix}A=210121012. Which of the following statements about AAA are true?
The determinant is 444
The eigenvalues are 2,2±22, 2 \pm \sqrt{2}2,2±2
It is positive definite
It is singular