Proof 1:
This picture implies
Proof 2:
Firstly, we have
then we assume
next, there has
hence, by Mathematical Induction, we can assert that
Proof 3:
Initially, note that
thus
where the red summation can be refered in the nether answer
therefore
Proof 4:
Let
then
It's characteristic equation is
which means
so we can set
Note that
, , , ,
We could solve by the above informtion, finally we get