Solution
= Solution
Expanding the <determinant> along the first row gives
$$
\boxed{\det A=1(-2-1)-2(0+1)+(-1)(0-1)=-4.}
$$
In particular the matrix is invertible.
= Solution
Expanding the <determinant> along the first row gives
$$
\boxed{\det A=1(-2-1)-2(0+1)+(-1)(0-1)=-4.}
$$
In particular the matrix is invertible.