Emathhelp

I haven't used it much, but it seems like a great way to get help (and answers if that's all you really want). It not only gives you an answer, like I just said, but it also gives you step by step instructions, for completely free which is really rare. This website is great for people who either want to get their homework done in a short time, or just want to understand more about certain topics.

P.S. The image tagged shows quite a simple problem, but there is much more advanced stuff on the website.