Originally Posted by
Ackbeet Hmm. Two comments:
1. Your fourth line doesn't look like that at all.
2. I don't think that's the right ERO for this stage in the game. I would do 3rd - (2nd x ($\displaystyle \alpha$-3)).
Come to think of it, that's what your fourth line looks like. I got your numeral 1's mixed up with your parentheses (maybe you should make your parentheses more curved, so they don't get confused with 1's). You actually did what I suggested in my second comment.
[EDIT]: I think you edited your post. Pick up my comments from here on down.
So I now follow you down to the fifth line. Your row reduction is correct, I believe.
Your logic is incorrect in your answer to i. In order for that entry in the matrix to be nonzero, you must have both $\displaystyle \alpha\not=2$ and $\displaystyle \alpha\not=1,$ (not or, as you wrote).
I would agree that for ii, it's impossible. And I agree with your answer for iii.
Does that help?