Let me run through this one.
I presume you've already done the base case so I won't redo that.
We are assuming that, for some value of k:
We need to show that this is true for the k + 1 case. So consider
But we know that
We also know that
<-- This step is easy to show. I leave it to you.
The lines I have labeled as (1) and (2) are what I think your lines 1 and 2 are meant to have been.