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Mentor
There you go avoiding the question yet again. By construction N has to be an integer. You can't say f(x)=x+x+... (3.5 times) because that doesn't make sense. You can have f(x)=x+x+x, which is 3 times, or you have have f(x)=x+x+x+x, which is 4 times.

Would you, in your next post, EITHER answer the question OR concede that I am right.
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~ Б0ЯИ Τ0 С0δЭ ~
x + x + x ... (x times) simply means x*x.

You can't claim f(x) = x + x + x or f(x) = x + x + x + x.
Because you can't fix x and then define f(x).

Even you know you are wrong, 'coz even Dr.Maths says so ... but I know your ego won't stop you from posting another vague argument. Go on ..
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Invasive contributor
@XP
http://mathforum.org/library/drmath/view/53415.html
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Invasive contributor
according to xp
Quote:
f'(x)=d/dx x + d/dx x + d/dx x... (x times)
and since d/dx x = 1, f'(x)=1+1+1... (x times) = x.
but according to a mathematician

Quote:
The correct way to do this is
y = x^2 = x+x+x+...+x (x times)
y' = (1+1+1+...+1) + (x) <-- 1 time!
<--x times-->
= x + x = 2x.
???
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Mentor
Why can't I define f(x)=x+x+x? Would you please explain that?

I don't know I'm wrong. In fact I'm sure I'm right because despite asking you repeatedly for an example of N where the equations don't hold you still haven't answered it.

You and Dr Math are both making the same mistake. f(x)=x+x+x...(N times); N=x; does
Code:
`***>>> NOT <<< ***(highlighted for clarity)`
mean f(x)=x^2.

x+x+x...(N times) = x^2 ONLY when N=x and at no other time. Suppose N=4 and f(x)=x+x+x+x. Then f(x)=16 and g(x)=x^2=16. But if we increase x to 5 while keeping N fixed at 4 then x+x+x+x=20 and x^2=25. So f(x) does not equal g(x) when x!=4.

Here are two examples of N where the equations DO hold.

Reminder: define f(x)=f1(x)+f2(x)+f3(x)+...+fN(x) where fp(x)=x for p=1..N. Also we set x=N.

(Example1) N=3 so f(x)=x+x+x and if x=N then f'(x)=1+1+1=3, g(x)=x^2=9 and g'(x)=2x=6. So f'(x) != g'(x) because 3!=6.

(Example2) N=4 so f(x)=x+x+x+x and if x=N then f'(x)=1+1+1+1=4, g(x)=x^2=16 and g'(x)=2x=8. So again f'(x)!=g'(x) because 4!=8.

So Saswat, mayjune and everyone else, I have given you TWO examples where f(x)=g(x) and f'(x)!=g(x). All I'm asking for is ONE SINGLE VALUE OF N where the above does not work and I will concede that I am wrong.
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~ Б0ЯИ Τ0 С0δЭ ~
Quote:
Originally Posted by xpi0t0s
You and Dr Math are both making the same mistake.

....<same vague things>....

So Saswat, mayjune and everyone else, I have given you TWO examples where f(x)=g(x) and f'(x)!=g(x). All I'm asking for is ONE SINGLE VALUE OF N where the above does not work and I will concede that I am wrong.
Yeah .. yeah.

You win. Live happily with your vague arguments.
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Invasive contributor
I think you are contradicting yourself xp....

Quote:
f(x) = x+x+x... (x times)
g(x) = x^2

Obviously f(x) = g(x), for example
if x=4 then f(x)=x+x+x+x = 4+4+4+4 = 16
if x=5 then f(x)=x+x+x+x+x = 5+5+5+5+5 = 25
You posted this, you never mentioned any x = N...
And now you saying

Quote:
f(x)=x+x+x...(N times); N=x; does
NOT
mean f(x)=x^2.??
???
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Invasive contributor
I think you are contradicting yourself xp....

Quote:
f(x) = x+x+x... (x times)
g(x) = x^2

Obviously f(x) = g(x), for example
if x=4 then f(x)=x+x+x+x = 4+4+4+4 = 16
if x=5 then f(x)=x+x+x+x+x = 5+5+5+5+5 = 25
You posted this, you never mentioned any x = N...

And now you saying

Quote:
f(x)=x+x+x...(N times); N=x; does
NOT
mean f(x)=x^2.??
???
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~ Б0ЯИ Τ0 С0δЭ ~
@ mayjune :

He has the right to contradict : his own views, mathematics and probably everything else too.
My prediction : he will still ask you for his N ... lol
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Mentor
> You posted this, you never mentioned any x = N...

Yes, that's right. I added the N part in afterwards when it was clear that x+x+x...(x times) was ONLY being interpreted as x*x, so it was for clarity. x+x+x... (N times) and x=N makes the original intent much clearer. I don't think a clarification constitutes a contradiction.

But still no N where it doesn't hold. I wonder why that's not possible, given how obviously wrong and silly and all the rest of it I'm supposed to be.