​Graph the square whose vertices are the points $(0, 0), (1, 0), (1, 1),$ and $(0, 1)$.  

1. What is the image of the square after a transformation by the matrix $\left[ \begin{array} { c c } { 2 } & { - 1 } \\ { 1 } & { 1 } \end{array} \right]$? Graph this image.

   Step (a):

   $\begin{bmatrix}2&-1\\1&1\end{bmatrix}\begin{bmatrix}1\\0\end{bmatrix}=?$

2. What is the geometric name of the image figure?