I have a question which asks me if the following two definitions of a derivative is equal. So I know the following equation,
$f'(x_0) = \lim_{h \to 0} \dfrac{f(x_0+h) - f(x_0)}{h} $
as we went through it when I learnt this and how to get the derivative using limits as h goes to $0$ but I don't get the following equation.
$g'(x_0) = \lim_{h \to 0} \dfrac{g(x_0+h) - g(x_0-h)}{2h} $
The question is asking me knowing that we defined a derivative of $\ f$ at $\ x_0$, is the following definition suggested by someone as equivalent and if so why? How would I go about answering this? Super confused about where to start?