Code has already been provided to define a matrix variable A with rows and columns. Add commands to perform the operations described below and assign the results to the indicated variable names.

Create a matrix B$1$ that consists of the first and last rows of A$.$

Create a matrix B$2$ that consists of the first and last columns of A$.$

Create a matrix B$3$ that consists of the elements at the four corners of A$.$

Create a matrix B$4$ that consists of the second through second last columns in the second through second last rows of A$.$

Create a matrix B$5$ that consists from the even$-$numbered rows of matrix A$,$ i$.$e$.,$ rows $2,4,6,...$

Create a matrix B$6$ that consists from the columns of matrix A at descending positions from the right of matrix A in decrements of $3,$ i$.$e$.,$ columns $,,,...$

Create a matrix B$7$ as a copy of matrix A with all positive elements replaced by their square root.

Create a sorted column vector b$8$ that contains all the values in matrix A in the interval $[-1,1]$ in descending order.

Create a matrix B$9$ that contains the rows $[3,1,4,3,2]$ and columns $[2,3,2,4,1]$ of matrix A in this order.