Question

Which matrix is an identity matrix?

Options

• \[\begin{bmatrix}1&0&0\\0&1&0\\0&0&1\end{bmatrix}\]

• \[\begin{bmatrix}2&0&0\\0&2&0\\0&0&2\end{bmatrix}\]

• \[\begin{bmatrix}1&1&0\\0&1&0\\0&0&1\end{bmatrix}\]

• \[\begin{bmatrix}0&0&0\\0&0&0\\0&0&0\end{bmatrix}\]

Answer 1

The first matrix has \[1\] on every diagonal position and \[0\] elsewhere. Thus, it is an identity matrix.