Math Is Fun Forum

aizeltine

Member

Registered: 2011-12-21

Posts: 2

Calculus Derivative help?

Calculus Derivative help?
when x = 0, f=2, f '=1, g=5, g '= -4
when x = 1, f=3, f '=2, g=3, g '= -3
when x = 2, f=5, f '=3, g=1, g '= -2
when x = 3, f=10, f '=4, g=0, g '= -1
based on the above table, if a = f +2g, then a'(3) =?
please show steps.thanks

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Calculus Derivative help?

Hi aizeltine;

I do not know if this will work every time but to find a'(3) add f'(3)+2g'(3) = 4 + -2 = 2 which is correct. I have tried the idea on a couple of others and it works.

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,649

Re: Calculus Derivative help?

hi aizeltine and bobbym,

Yes it will.

If

Bob

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Calculus Derivative help?

Hi bob bundy;

That is the definition of the derivative of a linear function. I guess it is okay then. Funny thing is in all the time I have played with and looked at methods of dealing with tables of data to curve fit I have never seen that ever used.

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,649

Re: Calculus Derivative help?

hi bobbym

How are you today?

What exactly do you mean by a 'linear function'?

I think I can prove it for the addition (and multiplication by a constant) of all pairs of differentiable functions.  I hope! 

Bob

Last edited by Bob (2011-12-21 23:54:10)

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob