For Lesson 8, Just a few minor mistakes (possibly typos): (1,3/5) should be (-1,3/5) in column 2 and you should have -5.-4,-3,-2,-1 as your new X values. Also (3,-125) should be (3,-375) as well as (-3,2/5) should be (-5,7/5).
Your thinking is correct though for that lesson but you got quite a few errors in the final numerical answer.
Lesson 7 looks pretty good.
For Lesson 9 (the very last question), recall that if you have y = a^x then log_a(y) = x where log_a(y) = ln(y)/ln(a) and log_a is the logarithm in base a (if it exists).
This will give you an exact answer and a good enough approximation on the calculator without needing trial or error.