where a = 5 and h = 1
Or did it indeed ask exactly as you had said, to simply calculate the value of the function?
(I know, this may seem like an unneccesary post, but I am just trying to make sure it wasn't the limit that they were asking you to calculate, since something of the form:
is used in problems with limits very, very, very often. And since this question is in the calculus thread area.)