Chegg is a wonderful site to buy, sell, or rent text books. Also, it has a innovative academic hub which helps students w/ course work, a planner, textbook solutions, and more. Chegg also has a very nice feature which helps students w/ their homework by searching textbooks or by entering a question and getting answers in an interactive community.
I highly recommend checking out Chegg for homework help.
*Chegg is a paid advertiser of Technology Tidbits.