 Solution

ID: past-exam-of-the-year-1-of-the-computer-science-course-of-the-university-of-oxford/2016/digital-systems-linear-algebra-introduction-to-formal-proof-resit/5/b/solution

Undo each elementary row operation: divide row 3 by 3, add 3 times row 2 to row 4, and repeat the same swap. Hence

E_{s}^{- 1} = 10000100 00 1/3 0 0001, E_{a}^{- 1} = 1000010300100001, E_{p}^{- 1} = E_{p} .

Multiplying each inverse by its original matrix gives the identity matrix.

 New to topics? Read the docs here!