"Could you help me with this homework?" Or "Can you help me with this homework?"
Use "could": it's more polite in asking questions. (And "Can you help me?" can also mean "Do you have the ability to help me?")
Read this: http://tmblr.co/Z90tLy10f-cXp
Read this: http://tmblr.co/Z90tLy10f-cXp