Question

Use the definition of the derivative to calculate f'(8) where f(x) = x+3.

Answer 1

Oh, you have to use the first principle? Not fun.

Answer 2

f'(x) = lim (as x -> 0) of [f(x+h) - f(x)] all over h.

Answer 3

I'm sure you know that. You can just substitute x-3 for f(x) and then substitute 8 for x--then solve to find f'(8).

Answer 4

Let me find a picture of the first principle anyway.