How do you know when somebody rejects your friend invite on Facebook?

Facebook won't let you know if someone rejects you- as in they won't send you an email to notify you. The only way to tell is to search for the person again or view their profile. If it says something like "Add as friend" then you know they denied your request because if they hadn't responded to it yet, it would say something along the lines of "There is a pending friend request".





Other than that, try contacting the person directly via AIM, email, phone, message.
How do you know when somebody rejects your friend invite on Facebook?
Honestly, the best way to know is to ask them. Send them a message or talk to them in person, another way is to look and see if anyone else has exchanged a message with them/written on wall, after you sent the friend request.