How do you find the derivative of a graph?

Question

anonymous · Answer

I am sure graphs don''t have derivative

anonymous · Answer

if you mean derivative of the equation of a graph

anonymous · Answer

draw tangent line at a point in the graph

anonymous · Answer

yes thats what I mean!

anonymous · Answer

You don't, you find the derivative of a function (the bit after the =)

anonymous · Answer

"yes thats what I mean!" Continue...

anonymous · Answer

U want to know how to do this

"draw tangent line at a point in the graph"

?? 

This answer your question?

anonymous · Answer

imranmeah91 is right. If all your given is the graph look at the slope(s) of the graph at any point(s). That's the derivative. The slope is the derivative.

myininaya · Answer

i look for where the function as horizontal tangents first
and where the graph has horizontal tangents that is where f' has 0 value
then i look before and after each number satisfying f'=0 
if the curve is increasing, then f'>0
if the curve is decreasing, then f'<0
there is also a few other things that we can talk and what to look for like if f approaches infinity near x=a, then notice that the slopes of the tangent line near a are getting closer and closer to a vertical line this would imply that f' will approach infinity near x=a

myininaya · Answer

also if f does not exist at x=b, then f' does not exist at x=b

anonymous · Answer

ok