just learned derivatives in calculus, but i have trouble to findin from f(3) to f'(x) on the graph.?

Question

if f(3), find f"(x)??

I know the f'(x) is the slope of the tagent line, but how to calculates it.. I have a hard time to find out..

thx

Answer 1

If you do have the graph, draw the tangent line and then get the slope of it. It's that or get the slope between the point you are given and a point really close to it, which is the tangent's slope.
If not, then you need the equation of f(x).

Answer 2

You can't find f'(x) from f(3) alone. What is the formula for f(x)?