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what does f'(x) actually mean?

i understand f(x) is the function of x. but when i get questions asking me to find f'(x) i don't understand what they mean?!

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Differentiate f(x)
Reply 2
That's the first derivative of the equation
So imagine the first equation is f(x) =
Thats the same as y=
So, f'(x)
Is dy/dx
your need to differentiate f(x)
The derivative with respect to x.
f'(x) is usually taken to be the derivative of f(x), i.e. the function you get after differentiating f(x)
Reply 6
It's the derived function: differentiate whatever f(x) is and you've found f'(x).

If y=f(x) then dy/dx=f'(x)
thank you guys! i'm not exactly the best mathematician out there! :biggrin:
Reply 8
stainless-style
thank you guys! i'm not exactly the best mathematician out there! :biggrin:


Well tbh knowing that f'(x) means differentiate f(x) with respect to x isn't really a question of being a good mathematician or not!! The whole point is that first of all you should learn the notation, either from a book or because a teacher has introduced it to you, and then you tackle problems that use this notation.

Have you not come across it in class or in a textbook before?
Reply 9
Unparseable latex formula:

\mbox{f}'(x) = \frac{d}{dx}(\mbox{f}(x))

. Thread over. :p:
davros
Well tbh knowing that f'(x) means differentiate f(x) with respect to x isn't really a question of being a good mathematician or not!! The whole point is that first of all you should learn the notation, either from a book or because a teacher has introduced it to you, and then you tackle problems that use this notation.

Have you not come across it in class or in a textbook before?

i've only seen it as dy/dx :frown: but atleast i'll know from now on!
f''(x) means differentiate f'(x). i.e. d2y/dx2

"The second derivative". f with two dashes :P Just differentiate f'(x)

(Just added that in as I thought it would be helpful)
Reply 12
Hey guys, i was wondering if someone could help me...

I have an average cost equation of:

AC= 4q^2 - 3q + 2 + 0.25/q

Can someone please help me work out the first and second derivative, the fraction in there is confusing me quite badly.......

Thanks in advance
Rewrite 0.25/q as 0.25q^-1, and differentiate as usual.
Reply 14
cheers mate, so it would be

Ac' = 8q - 3 - 0.25/q^2? ........i think
Saiko21
cheers mate, so it would be

Ac' = 8q - 3 - 0.25/q^2? ........i think


Yes, that's right.
Reply 16
ok another similar question lol. sorry bout this....

I have p=100-5.5q
I worked out q to be q = p/5.5+100

wat is the first derivative of Q??

thanx
f(x) is a function of x, but f'(x) is the derivative with respect to what seems to make sense. In terms of a-level f'(x) pretty much means dy/dx, but you should realise that d(f(x))/dx = f'(x) doesn't require a y.
As for the post, it depends what you are differentiating with respect to but I assume it is p (i.e. do you want dq / dp ?). Btw, q = (100 - p) / 5.5, then also q = 100/5.5 - p/5.5, now if I said q = y, and p = x, then y = 100/5.5 - x/5.5. Can you find dy/dx?
Saiko21
ok another similar question lol. sorry bout this....

I have p=100-5.5q
I worked out q to be q = p/5.5+100

Afraid not...
Most common notation, it names the independent variable and emphasize the function's name .

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