A small mistake was found in Unit #1, Lesson #4, Exercise #5 (from the lesson). The final answer to part (e) should be slightly different, i.e. 6x^4y^5. Here’s the new answer key:
CCAlgII.Unit #1.Lesson #4.Basic Exponent Manipulation.Answer Key
Thanks to Tracey Finan from Croton-Harmon for finding this mistake.