11. Determine if each of the following operations is a linear transformation (explain why).
If it is, find the matrix that represents it and write the transformation in the matrix form.
(a) $T: \mathbb{R}^3 \to \mathbb{R}^3$, $T([x, y, z]) = [x - y, x + z, y]$.
(b) $S: \mathbb{R}^3 \to \mathbb{R}^3$, $S([x, y, z]) = [0, y + 2, z]$.