1) seems like it shouldn't be too difficult. I don't get what I'm trying to prove though. How would the value of be able to show that it is not solvable? I know is always even when . But is always going to be even, so I'm confused as to how I prove this.

2) I don't even understand how I recursively go back and do this.

f*f{-1} = i, and set i = summation....