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The "-ation's" in core 1

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Reply 20
Original post by Cephalus
the 'fancy S'??


But that's exactly what it is. :tongue:
Original post by PointyElbow
If it's already been differentiated, the equation will be dy/dx=.....
or f'(x)=.....
the apostrophe means it's the differential of f(x)


Thank you ! The f'(x) thing is what I was looking for !


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Original post by TenOfThem
Actually this is really naive as the terminology is very important


I was being genuine o.O
I honestly didn't realise that knowing the name of the symbol was important.


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Original post by JessCarey
I was being genuine o.O
I honestly didn't realise that knowing the name of the symbol was important.



It is not about the "symbol" it is about the concept of integration ... and knowing the term
I know what to do I just wanted some definite clarification on which was which,it was just an easier way to remember it


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Reply 25
Original post by JessCarey
I know what to do I just wanted some definite clarification on which was which,it was just an easier way to remember it


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Once you've practised these things a zillion times they will become second nature to you, and you'll wonder how you could ever confuse the two.

If you see an expression like dy/dx then the 'd' is telling you that differentiation is involved - but you need to be careful because if y = f(x) then you might also see the notation f'(x) used to denote the derivative of f with respect to x. (Occasionally also in older mechanics texts you may see a letter with a dot over the top of it, which indicates differentiation with respect to time).

When you have an integral sign f(x)dx\int f(x) dx, this tells you that you are working out "the integral of f(x) with respect to x" (the 'dx' bit here tells you that the integral is "with respect to x").

The terminology isn't there to make life harder - it's to help you be precise about what it is you're trying to do. If you get in the habit of writing out the English equivalent of what you're doing then not only does it help you to organize your thoughts but it might also encourage an examiner to give you the benefit of the doubt if it's not clear what you're trying to do, e.g.

"To work out the point where y has a minimum, we need to differentiate y with respect to x, so we calculate dy/dx = ..." etc

There aren't actually all that many terms to learn, so the more you use them the more familiar they become.

(And the integral sign is an elongated 'S' - it indicates that integration can be though of as the continuous equivalent of the sum of a discrete number of terms, so we use \int instead of \sum )

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