simple question

[Kobu]

Is d(g+f) / dt = dg/dt + df/dt

[Say g and f are 2 "lengths" that are changing]

What is the proof of this?

 

[Kobu]

Is d(g+f) / dt = dg/dt + df/dt

[Say g and f are 2 "lengths" that are changing]

What is the proof of this?

Sorry big mistake. Not supposed to be in this NG.

 

[CBFalconer]

Is d(g+f) / dt = dg/dt + df/dt

[Say g and f are 2 "lengths" that are changing]

What is the proof of this?

Sorry big mistake. Not supposed to be in this NG.

With that understood, write down the delta expressions and take the
limit as delta t approaches zero. Do not respond here.

--
"The power of the Executive to cast a man into prison without
formulating any charge known to the law, and particularly to
deny him the judgement of his peers, is in the highest degree
odious and is the foundation of all totalitarian government
whether Nazi or Communist." -- W. Churchill, Nov 21, 1943

 

[Martin Ambuhl]

Is d(g+f) / dt = dg/dt + df/dt

[Say g and f are 2 "lengths" that are changing]

What is the proof of this?

Your question is obviously not about C, and so off-topic. But it is
easy enough to answer:

It is true that
d(g+f)/dt = dg/dt + df/dt

If you actually need to find a proof, check the very early parts of an
elementary calculus text. But you should be able to work this out for
yourself in almost no time at all. You should have learned that
if the differential quotient
(u(t+h) - u(t))/h
has a limit as h -> 0, that limit is the derivative du/dt
Using this with u = g+h, prove the required formula for yourself. It
takes no longer than just writing it down.