Hello, qzno!
I have a "2" where you have "8".
I did it differently and got an entirely different-looking answer.
Watch this . . .
Take logs: .
Then: .
Therefore: .
In the last two, be careful with your algebra.
. . You missed a "minus" in both of them.
We have: .
Take logs: .
. .
. .
. .
Got it?