Dear Jake,

 Please consult

https://sites.math.rutgers.edu/~zeilberg/Hist21/q6S.pdf

for the full solutions.

You got 7 points (out of 10).

For #4 you used a differemt method than waht I taught, that is perfectly OK, but you messed up the caluclations and got wrong answers.
You should have checked at least that the root x=3 that you got was wrong by plugging-in the cubic and realizing that it was an error.

 Best wishes,

   Dr. Z.