Problem involving derivative and left-hand limit

[Loopas]

This is from an online homework that's due in an hour. This question has been bothering me all day and I'm convinced that there's a problem with the website.

It's asking for the expression that's used to find the left-hand limit of the derivative, f'(0).

It won't take 2x+6 as the answer... Am I missing something or is the website just screwed up?

I attached a picture of the problem. Help fast!

 

[klondike]

Do you remember the derivative of of $$x^n$$?

 

[Loopas]

Wouldn't that be n?