Dear Vivian,

 Please consult

https://sites.math.rutgers.edu/~zeilberg/Hist21/q2S.pdf

for the full solutions.

You got 7 points (out of 10). 

You sraated number #5, but in a wrong way. A(0)=0 not -1.

For #4 you should have explained more, but this time I did not take times off.

 Best wishes,

   Dr. Z.