If you submitted the early homework by 5:00 Wednesday, you don't need to turn in problems 2.1 #11, 2.2 #27, 2.3 #5 and 31, or 2.4 #15 on Friday. Question 1: Let B be a 3 by 3 matrix, and let C be the matrix obtained from B by adding twice row 1 to row 3, and switching row 1 with row 2.
Find a matrix A such that C=AB. (No justification is required.)
Question 2:

Let N=

1 3 0 3 10 0 0 -3 1

.

N is invertible. Find N^-1. Show every step in your work.
Question 3: Let I represent the nxn identity matrix, and let A be any nxn matrix.

Let E be the block matrix

I 0 0 0 I 0 A 0 I

.

Is E invertible? If so, find E^-1.
(Hint: If n=1, you could write down the answer without doing any work. Will the same techniques apply in general?)

---