Do not, however, submit your assignments in batches. You'll be better prepared for each assignment if you can take advantage of your instructor's evaluation of one assignment before you submit the next. Continue with your reading and assignment preparation while you wait for the return of your previous assignment. If you submit multiple assignments they will be returned to you ungraded, unless you have written permission from your instructor to submit more than one assignment at a time. There are mistakes in the answers.
Space is at a premium in any textbook.
The answer in the book may have been manipulated to fit into a given space, and therefore looks different. Your answer might, in fact, be wrong. Compare your answer with the book's and use the similarities and differences to focus on the particular spot where you disagree. If you still can't find the error, look at other problems similar to the one you just did. If you're answers agree on four out of five problems, you understand the concept and you can safely forget this problem.