∞ if y ‡ 0 and yn #0 for all n € N, then (2) 1 converges to Yn n=1 ৪১১

I have the following proof, i understand the injective proof but I have no clue how and why they do the surjective proof, is there a certain plan or steps I have to follow? Please explain in more detail and show why each step is taken

Discrete Math Prove

Example:3 Verify Cayley-Hamilton theorem, and find A-1 [2 A=0 1 [1 1 2.

Example:4 Verify Cayley-Hamilton theorem. Hence find 2 -1 1 A-1, A 1 2 -1 1 -1

Linear Algebra